Home

Challenging Glass Conference Proceedings collects the conference articles presented at the international bi-annual Challenging Glass Conference and focuses on the Architectural and Structural Application of Glass.

CONFERENCE HOSTSProf. Rob Nijsse Delft University of Technology, Delft, The NetherlandsDr Fred Veer Delft University of Technology, Delft, The Netherlands

CONFERENCE LOCAL ORGANISER SUPPORTMark Scholten Delft University of Technology, Delft, The NetherlandsBasia van Vliet Delft University of Technology, Delft, The NetherlandsBarbara van Vliet Delft University of Technology, Delft, The NetherlandsLinda Verschuren-van Rijsbergen Delft University of Technology, Delft, The NetherlandsTessa Vermeulen Delft University of Technology, Delft, The Netherlandsir. Lida Barou Delft University of Technology, Delft, The Netherlandsir. Telesilla Bristogianni Delft University of Technology, Delft, The NetherlandsClarissa Justino de Lima, MSc Delft University of Technology, Delft, The Netherlandsir. Faidra Oikonomopoulou Delft University of Technology, Delft, The Netherlandsir. Ate Snijder Delft University of Technology, Delft, The Netherlands

Keynote Contributions

Even with today’s technically advanced navigation systems, user experience situations where announcements are difficult to understand and misleading. Augmented reality – the integration of computer generated content into the vehicle surrounding – can provide an intuitive and unambiguous way to communicate navigation information; it can even serve as a novel user interface that allows interaction with the surrounding. In this paper, challenges, constraints, and possible solutions for AR in-vehicle applications are discussed. Details of the technical and design decisions of the “first in-vehicle augmented video system” are explained, as well as features and possible future upgrades.

Even with today’s technically advanced navigation systems, user experience situations where announcements are difficult to understand and misleading. Augmented reality – the integration of computer generated content into the vehicle surrounding – can provide an intuitive and unambiguous way to communicate navigation information; it can even serve as a novel user interface that allows interaction with the surrounding. In this paper, challenges, constraints, and possible solutions for AR in-vehicle applications are discussed. Details of the technical and design decisions of the “first in-vehicle augmented video system” are explained, as well as features and possible future upgrades.

Even with today’s technically advanced navigation systems, user experience situations where announcements are difficult to understand and misleading. Augmented reality – the integration of computer generated content into the vehicle surrounding – can provide an intuitive and unambiguous...

Architectural Design, Geometries & Lighting

This research investigates the potential of glass as a new design tool to highlight and safeguard our historic structures. Current restoration and conservation treatments with traditional materials bear the risk of conjecture between the original and new elements, whereas the high consolidation demands often result in visually invasive and irreversible solutions. Nowadays, aspects of materiality and aesthetics appear as integral parts of the restoration practices, indicating new materials and technologies in the form of ambiguous gestures rather than absolute and permanent manifestations that prevail over the historic structures. The inherent transparent properties render glass a distinct material that enables the simultaneous perception of the monument in both its original and ruinous state. The emerging technologies have set the ground for using glass in a structural way minimizing the need for substructure and maximizing transparency, while protecting the sensitive historic materials. The paper explores the feasibility of this concept addressing aspects of compatibility, reversibility and transparency, through a review of realized examples. Finally, a developed methodology relates the, available in the market today, glass products to the possible consolidation treatments in respect to the degree of intervention and representativeness, stressing the potential of using and considering glass as a promising restorative material.

This research investigates the potential of glass as a new design tool to highlight and safeguard our historic structures. Current restoration and conservation treatments with traditional materials bear the risk of conjecture between the original and new elements, whereas the high consolidation demands often result in visually invasive and irreversible solutions. Nowadays, aspects of materiality and aesthetics appear as integral parts of the restoration practices, indicating new materials and technologies in the form of ambiguous gestures rather than absolute and permanent manifestations that prevail over the historic structures. The inherent transparent properties render glass a distinct material that enables the simultaneous perception of the monument in both its original and ruinous state. The emerging technologies have set the ground for using glass in a structural way minimizing the need for substructure and...

This research investigates the potential of glass as a new design tool to highlight and safeguard our historic structures. Current restoration and conservation treatments with traditional materials bear the risk of conjecture...

The economy globalizes. The industries concentrate. The productions become uniform. Cultural specificities disappear. About architecture and glass in architecture, it is the same phenomenon. Is this movement good or not? It is too late to ask the question. This dynamic is irreversible. Nevertheless, in certain cases, on certain projects, it is possible to bring more esthetic, sensibility, humanity and culture. The 100 years of Ferro’s experience in material science provide such base for creativity with outstanding material solutions like s1de ONE and LustReflex. Since 20 years, the Barrois Glass studio works to create bridges between crafts and industry with the objective in esthetic, sensibility, humanity and culture. Associate the rigor and the efficiency of the industry with the creativity and the sensibility of crafts. A decade of s1de ONE projects proving the durability at challenging environmental conditions is reviewed. The latest material developments and application technologies providing new opportunities for creativity is shown. The three outstanding projects—La canopée les Halles in Paris, Le frac in Marseille, Le musée de la Romanité in Nîmes— are presented in detail. Those projects were all studied with the objective to work otherwise.

The economy globalizes. The industries concentrate. The productions become uniform. Cultural specificities disappear. About architecture and glass in architecture, it is the same phenomenon. Is this movement good or not? It is too late to ask the question. This dynamic is irreversible. Nevertheless, in certain cases, on certain projects, it is possible to bring more esthetic, sensibility, humanity and culture. The 100 years of Ferro’s experience in material science provide such base for creativity with outstanding material solutions like s1de ONE and LustReflex. Since 20 years, the Barrois Glass studio works to create bridges between crafts and industry with the objective in esthetic, sensibility, humanity and culture. Associate the rigor and the efficiency of the industry with the creativity and the sensibility of crafts. A decade of s1de ONE projects proving the durability at challenging environmental conditions is reviewed. The...

The economy globalizes. The industries concentrate. The productions become uniform. Cultural specificities disappear. About architecture and glass in architecture, it is the same phenomenon. Is this movement good or not? It is too late to ask the...

Serrated building envelopes are a very eye-catching element of contemporary architecture. This type of façade in plan resembles the edges of a serrated blade, hence the name. Serrated facades substantially influence the building’s tectonics understood as the relationship between the structural and the artistic form. They also have a major impact both on building physics (increased surface of heat exchange compared to flat facades, solar avoidance – decreased solar gains if properly designed) and on visual appeal. This article examines façade morphology and analyzes the influence of its geometry on the aesthetic quality of the envelope. The morphological analysis includes the serration angle between the wings (acute or obtuse), wing proportions, and façade depth. An exceptional feature of serrated façades is that the optical phenomena on the façade change depending on the viewing angle. This paper discusses various perceptual zones that produce different phenomena, e.g.: (i) single wing visibility, (ii) mutual wing self-reflection, (iii) primary and secondary virtual The presented paper is based on case studies with special attention to morphological and qualitative analysis. Cases serve as visual (photographs) and graphical illustrations(diagrammatic drawings). The paper also includes a brief presentation of selected recently completed case studies.

Serrated building envelopes are a very eye-catching element of contemporary architecture. This type of façade in plan resembles the edges of a serrated blade, hence the name. Serrated facades substantially influence the building’s tectonics understood as the relationship between the structural and the artistic form. They also have a major impact both on building physics (increased surface of heat exchange compared to flat facades, solar avoidance – decreased solar gains if properly designed) and on visual appeal. This article examines façade morphology and analyzes the influence of its geometry on the aesthetic quality of the envelope. The morphological analysis includes the serration angle between the wings (acute or obtuse), wing proportions, and façade depth. An exceptional feature of serrated façades is that the optical phenomena on the façade change depending on the viewing angle. This paper discusses various perceptual zones that produce different phenomena, e.g.:...

Serrated building envelopes are a very eye-catching element of contemporary architecture. This type of façade in plan resembles the edges of a serrated blade, hence the name. Serrated facades substantially influence the building’s tectonics understood as the relationship between the...

Defined by the building law in each publicly accessible building (e.g. schools, administration etc.) emergency exit routes have to be marked usually by means of active or passive lightening systems. The use of passive lightening systems require comprehensive components with an independent, battery-powered energy-supply that produces light even in the case of an energy black-out (e.g. disaster situations). The use of powerlines plus the frequently service of battery-powered systems is complicated and expansive. Alternatively after-glowing, phosphorescent signs, attached on walls, wallpapers or doors are an existing alternative. Mostly known to everybody are the green emergency exit signs. Furthermore phosphorescent paints on floors or walls are also used to guide people on the quickest escape way. Used inside of buildings their appearance has mostly a disturbing and negative attitude, even more at premium interior designs. Therefore, the composition of passive lightened systems with premium-quality surfaces leads to a widely usable product phosphorescent glass. This glass consists of laminated glass with a phosphorescent paint application within the glass interlayer. The paper describes the research and development of phosphorescent glass with a strong emphasis on materials testing, application technics and the behavior as laminated safety glass.

Defined by the building law in each publicly accessible building (e.g. schools, administration etc.) emergency exit routes have to be marked usually by means of active or passive lightening systems. The use of passive lightening systems require comprehensive components with an independent, battery-powered energy-supply that produces light even in the case of an energy black-out (e.g. disaster situations). The use of powerlines plus the frequently service of battery-powered systems is complicated and expansive. Alternatively after-glowing, phosphorescent signs, attached on walls, wallpapers or doors are an existing alternative. Mostly known to everybody are the green emergency exit signs. Furthermore phosphorescent paints on floors or walls are also used to guide people on the quickest escape way. Used inside of buildings their appearance has mostly a disturbing and negative attitude, even more at premium interior designs. Therefore, the composition of passive lightened systems...

Defined by the building law in each publicly accessible building (e.g. schools, administration etc.) emergency exit routes have to be marked usually by means of active or passive lightening systems. The use of passive lightening systems require comprehensive components with an independent,...

The purpose of this paper, as part of a MSc graduation project, has been to explore to which extent the kinematic potential of folded geometries can benefit from the structural and architectural properties of glass plates. Using as a case study the covering in an adjustable way an outdoor swimming pool area, the course of this paper consists of form evolution based on structural performance and development of a dual purpose connection and deployment principle developed through experimental testing. Both aspects are examined independently, in parallel processes, and the findings are combined and further evaluated. This study has shown that it is possible to create a self-supporting structure made out of plate elements which is also directionally deployable, without compromising the system’s stability and thus provides an important beginning to implementing complex structures that make use of the benefits of glass.

The purpose of this paper, as part of a MSc graduation project, has been to explore to which extent the kinematic potential of folded geometries can benefit from the structural and architectural properties of glass plates. Using as a case study the covering in an adjustable way an outdoor swimming pool area, the course of this paper consists of form evolution based on structural performance and development of a dual purpose connection and deployment principle developed through experimental testing. Both aspects are examined independently, in parallel processes, and the findings are combined and further evaluated. This study has shown that it is possible to create a self-supporting structure made out of plate elements which is also directionally deployable, without compromising the system’s stability and thus provides an important beginning to implementing complex structures that make use of the benefits of glass.

The purpose of this paper, as part of a MSc graduation project, has been to explore to which extent the kinematic potential of folded geometries can benefit from the structural and architectural properties of glass plates. Using as a case study the...

Cast glass components are a promising solution for engineering pure glass structures of high transparency and load-carrying capacity due to their large cross-sectional area and monolithic nature. Currently, the few realized structures employing cast glass components rely either on a steel substructure or on an adhesive of high bonding strength and typically less than 2 mm thickness, to ensure the stiffness and stability of the construction. Whereas the first solution compromises the overall level of transparency, the second results to a permanent construction requiring intensive and meticulous labour and extreme accuracy. This paper explores the potential of a novel, reversible all-glass system comprising dry-assembly, interlocking cast glass components as a promising and sustainable solution that can avoid the above-mentioned challenges. Owing to its interlocking geometry, the proposed system can attain the desired stiffness and stability with the aid of minimal, if any, metal framing. Furthermore, the suggested system circumvents the use of adhesives by using a dry, colourless interlayer as an intermediate between the glass components to accommodate any dimensional tolerances and allow for an even load distribution; moreover, it allows for the disassembly and circular use of the components. To validate the concept, different component geometries and interlocking mechanisms are developed. As a proof of concept, the most promising interlocking forms are kiln cast in 1:2 scale and assessed in terms of mechanical interlocking capacity, mass distribution, residual stress generation and ease of fabrication. In parallel, research is conducted on different materials for the dry, transparent interlayer. From the developed designs, blocks with osteomorphic interlocking mechanisms are selected as the most promising concept and are further assessed by numerical modelling to study the influence of the interlocking geometry to the overall structural performance. The results highlight the structural potential of the proposed system and demonstrate its feasibility.

Cast glass components are a promising solution for engineering pure glass structures of high transparency and load-carrying capacity due to their large cross-sectional area and monolithic nature. Currently, the few realized structures employing cast glass components rely either on a steel substructure or on an adhesive of high bonding strength and typically less than 2 mm thickness, to ensure the stiffness and stability of the construction. Whereas the first solution compromises the overall level of transparency, the second results to a permanent construction requiring intensive and meticulous labour and extreme accuracy. This paper explores the potential of a novel, reversible all-glass system comprising dry-assembly, interlocking cast glass components as a promising and sustainable solution that can avoid the above-mentioned challenges. Owing to its interlocking geometry, the proposed system can attain the desired stiffness and stability with the aid of minimal, if any, metal...

Cast glass components are a promising solution for engineering pure glass structures of high transparency and load-carrying capacity due to their large cross-sectional area and monolithic nature. Currently, the few realized structures employing cast glass components rely either on a steel...

Curved & Bended Glass

Significant progress has been made during the past two decades to advance the use of cold warped glazing (glass that has been elastically twisted out of plane) to achieve architectural vision. As with most new technologies, a full understanding of the mechanics of elastic cold warping has lagged its adoption and increasing specification for use in new construction. As a contractor whose aim is to turn vision into reality, Enclos has been invested in research and development related to the structural and performance implications of cold warped glazing. One of the most recent discoveries from this work at Enclos has been to relate cold warping of glass to its effect on plate stiffness. In particular, transverse stiffness to resist load may be negatively affected by the operation of cold warping glass supported by a perimeter frame. This loss in stiffness has been observed in cold warped glass when compared to flat glass of equal size and thickness. Recent work at Enclos indicates deflection due to transverse load increases with an increasing degree of warping. This phenomenon is especially pronounced for thin plates that resist load through significant large-deformation, non-linear plate behavior. As the degree of warp increases, the loss of stiffness becomes increasingly apparent, to the point at which the glass buckles. As a result of the warping operation, compressive membrane stresses are generated in the center region of the glass. These compressive stresses counteract the tension that normally arises during large-deformation plate behavior and that contributes to its deflection performance. As such, a membrane compression due to warping leads to the loss in stiffness when membrane effects appreciably contribute to overall bending stiffness (as they do in plates that fall within the large-deflection regime of bending). An exploration of this phenomena using a series of finite element tests, coupled with observations from previous testing are the basis for these findings.

Significant progress has been made during the past two decades to advance the use of cold warped glazing (glass that has been elastically twisted out of plane) to achieve architectural vision. As with most new technologies, a full understanding of the mechanics of elastic cold warping has lagged its adoption and increasing specification for use in new construction. As a contractor whose aim is to turn vision into reality, Enclos has been invested in research and development related to the structural and performance implications of cold warped glazing. One of the most recent discoveries from this work at Enclos has been to relate cold warping of glass to its effect on plate stiffness. In particular, transverse stiffness to resist load may be negatively affected by the operation of cold warping glass supported by a perimeter frame. This loss in stiffness has been observed in cold warped glass when compared to flat glass of equal size and thickness. ...

Significant progress has been made during the past two decades to advance the use of cold warped glazing (glass that has been elastically twisted out of plane) to achieve architectural vision. As with most new technologies, a full understanding of the mechanics of elastic cold warping...

Research has shown that the general approach to determine the bending strength of thermally curved glass with the aid of the four-point bending test for flat glass according to EN 1288-3 is applicable. At the moment, however, there is no statutory method available for directly extrapolating the breaking strain from the breaking load without the use of expensive strain gauges. Such a method is developed by means of an experimental and numerical study in a research project between the Bundesverband Flachglas e.V. (Federal Flat Glass Association) and the Fachverband Konstruktiver Glasbau e.V. (Professional Association Structural Glass Constructions), the Institute of Building Construction at the Technische Universität Dresden and four glass bending specialists. Moreover, it will provide the basis for testing cylindrically curved glass of any bending radius. The project partners have already submitted a proposal for a new standard to the Deutsches Institut für Normung e.V. (German Institute for Standardisation). The paper gives the theoretical background for determining the strength of flat glass according to EN 1288‑3 and quantifies the additional effects for the testing of thermally curved glass. Furthermore, the testing method of the executed experimental study on thermally curved glass is described. The range of parameters for the tested specimens included the glass thickness from 3 mm to 12 mm and the bending radii from 400 mm to 2000 mm. We recorded the strain at selected points at the tensioned side and the input force for each specimen. The measured relation between strain and load validates a numerical model, which is able to depict the actual two-dimensional stress distribution for thermally curved glass and includes non-linear aspects. The model allows for the determination of correction factors. With those, the bending strength of thermally curved glass can be calculated by measuring merely the input force during the four-point bending tests. The correction factors are summarised in charts depending on the radius and the thickness of the glass sample.

Research has shown that the general approach to determine the bending strength of thermally curved glass with the aid of the four-point bending test for flat glass according to EN 1288-3 is applicable. At the moment, however, there is no statutory method available for directly extrapolating the breaking strain from the breaking load without the use of expensive strain gauges. Such a method is developed by means of an experimental and numerical study in a research project between the Bundesverband Flachglas e.V. (Federal Flat Glass Association) and the Fachverband Konstruktiver Glasbau e.V. (Professional Association Structural Glass Constructions), the Institute of Building Construction at the Technische Universität Dresden and four glass bending specialists. Moreover, it will provide the basis for testing cylindrically curved glass of any bending radius. The project partners have already submitted a proposal for a new standard to the Deutsches Institut für Normung e.V. (German...

Research has shown that the general approach to determine the bending strength of thermally curved glass with the aid of the four-point bending test for flat glass according to EN 1288-3 is applicable. At the moment, however, there is no statutory method available for directly extrapolating...

The owner of a 1970s, 24-story commercial office tower in Ottawa, Canada sought to rejuvenate their main lobby with a new glass entry wall. The wall’s purpose is to provide a notable, grand entryway for the re-development of a commercial podium on a main thoroughfare. The final design featured a 12 m tall by 35 m long curving glass fin wall. The height of the wall is broken up into two sections. The first is a 9 m tall section between the ground floor and a third-floor terrace that provides the main building with a new front entrance, including a double-height space. The second is a cantilevered 3 m tall balustrade that creates a new third floor terrace. The glass fins between the ground floor and third floor terrace are continuous, triple-laminated panels free of splices. The curved panels have a 30 m curvature radius and feature a ceramic frit to prevent bird strikes and promote environmental sensitivity. In addition, the panels are insulated glass units (IGUs) with a low-emissivity coating (low-e) to meet the City of Ottawa’s energy standards and the expected interior comfort of top tier retail and office space within the city. Furthermore, the glass panels are supported at discrete points, so the team used a composite resin as the laminate for the interior and exterior lites to maintain the cold bent curvature radius.

The owner of a 1970s, 24-story commercial office tower in Ottawa, Canada sought to rejuvenate their main lobby with a new glass entry wall. The wall’s purpose is to provide a notable, grand entryway for the re-development of a commercial podium on a main thoroughfare. The final design featured a 12 m tall by 35 m long curving glass fin wall. The height of the wall is broken up into two sections. The first is a 9 m tall section between the ground floor and a third-floor terrace that provides the main building with a new front entrance, including a double-height space. The second is a cantilevered 3 m tall balustrade that creates a new third floor terrace. The glass fins between the ground floor and third floor terrace are continuous, triple-laminated panels free of splices. The curved panels have a 30 m curvature radius and feature a ceramic frit to prevent bird strikes and promote environmental sensitivity. In addition, the panels are...

The owner of a 1970s, 24-story commercial office tower in Ottawa, Canada sought to rejuvenate their main lobby with a new glass entry wall. The wall’s purpose is to provide a notable, grand entryway for the re-development of a commercial podium on a main thoroughfare. The final...

Use of cold-bent and warped glass units in unitized curtain walling is becoming a state-of-the art application. During the last years, such a global trend has challenged the design and engineering of glass units, frame elements as well as bonding joints in Structural Sealant Glazing (SSG) applications and has pushed for the investigation of material performance and calculation concepts, beyond available standards and guidelines. It is clear today that in SSG systems cold bending retention forces and differential displacements play a major role in the system design and need to be properly controlled. With reference to SSG joints, investigation has focused on proposing simplified equations to evaluate cold bending stress and studying relaxation and creeping behavior of Sikasil® structural silicones to exploit material performance beyond standard limits. Such investigation process allows identifying where opportunities for systems optimizations are and clarifies that effective cold-bending solutions cannot be uncoupled from new principles of system design, pre-manufacturing and installation. The development of Mistral Tower in Izmir offers the chance to evaluate in detail the impact of different frame solutions in combination with different production and installation methods and is used to present to system designers and façade producers valuable options and guidelines for approaching design of cold-bent units effectively. The use of slim adapter frame bonded to glass units and free to slide into load-bearing frame represents the basic requirement to limit cold bending effects on SSG joints, while minimizing production efforts. Valuable optimization results can be further achieved if bonding on either pre-shaped frame or pre-shaped frame/glass assembly is possible or if cold-bending stress can be limited in time by a clever production method in controlled conditions. Advanced FE analysis simulating SSG joints by hyperelastic material law validate preliminary stress evaluation, criteria selection for unit manufacturing and final design choices in Mistral Tower construction.

Use of cold-bent and warped glass units in unitized curtain walling is becoming a state-of-the art application. During the last years, such a global trend has challenged the design and engineering of glass units, frame elements as well as bonding joints in Structural Sealant Glazing (SSG) applications and has pushed for the investigation of material performance and calculation concepts, beyond available standards and guidelines. It is clear today that in SSG systems cold bending retention forces and differential displacements play a major role in the system design and need to be properly controlled. With reference to SSG joints, investigation has focused on proposing simplified equations to evaluate cold bending stress and studying relaxation and creeping behavior of Sikasil® structural silicones to exploit material performance beyond standard limits. Such investigation process allows identifying where opportunities for systems...

Use of cold-bent and warped glass units in unitized curtain walling is becoming a state-of-the art application. During the last years, such a global trend has challenged the design and engineering of glass units, frame elements as well as bonding joints...

Chemically strengthened thin glass (t < 2 mm) is a material that is stronger and due to its small thickness, more flexible than conventional window glass. As such, thin glass offers the possibility for lightweight and flexible glass façades that could change shape depending on external conditions. This paper explores this concept and presents an MSc study on the use of this material in adaptive façade panels. The behavior of thin glass in this context depends on different factors. The glass thickness and strength define its bending limits, while the desired geometry and movement affect its overall stiffness and visual outcome. In order to integrate these factors, different configurations of panels were analyzed in numerical models. These analyses showed the importance of understanding the desired movement and geometry in order to correctly define the supports and degrees of freedom of the panel, avoiding stress concentration (particularly on the edges) and allowing for an unobstructed movement of the panel. The development of these analyses resulted in the conception of a design example of an adaptive façade panel, taking into consideration the design requirements developed in the research. Finally, as a proof of concept, a mock-up was built simulating the behavior of the design example developed in this research. Although there is still the need for research to be developed so that thin glass can become a building material, this research showed that this is possible and that interesting results, regarding visual effect, ventilation and dead load reduction (in larger scale, an environmental impact reduction is also possible) can be achieved. Besides that, using thin glass in adaptive panels challenges the concept of glass as a static material, opening new possibilities for its use.

Chemically strengthened thin glass (t < 2 mm) is a material that is stronger and due to its small thickness, more flexible than conventional window glass. As such, thin glass offers the possibility for lightweight and flexible glass façades that could change shape depending on external conditions. This paper explores this concept and presents an MSc study on the use of this material in adaptive façade panels. The behavior of thin glass in this context depends on different factors. The glass thickness and strength define its bending limits, while the desired geometry and movement affect its overall stiffness and visual outcome. In order to integrate these factors, different configurations of panels were analyzed in numerical models. These analyses showed the importance of understanding the desired movement and geometry in order to correctly define the supports and degrees of freedom of the panel, avoiding stress concentration (particularly on the edges) and allowing for...

Chemically strengthened thin glass (t < 2 mm) is a material that is stronger and due to its small thickness, more flexible than conventional window glass. As such, thin glass offers the possibility for lightweight and flexible glass façades that could change shape depending on external...

Glass in Facades

Although in theory glass can be endlessly remelted without loss in quality, in practice only a small percentage gets recycled, mainly by the packaging industry. Most of the discarded glass fails to pass the high quality standards of the prevailing glass industry -due to coatings, adhesives, other contaminants or incompatibility of the recipe- and ends up in the landfill. However, employing discarded glass in cast components for building applications can be a way to reintroduce this waste to the supply chain. Such components can tolerate a higher percentage of inclusions, without necessarily compromising their mechanical or aesthetical properties. This paper explores the potential but also the limitations of recycling glass in order to obtain load-bearing components. First, an overview is provided regarding which types of glass reach the recycling plants and the which not, arguing on the reasons behind this selection. Afterwards, a series of experiments is presented, exploring the possibilities of recycling everyday glass waste, from beer bottles and Pyrex® trays to mobile phone screens. Each type of glass waste is initially cast separately to define its flow capability and risk of crystallization. The above information is linked to the X-ray fluorescence (XRF) analyses of the samples prior to recycling. Then, the possibility to mix different glass recipes without fracturing is evaluated. The results point out the types of glass with potential in structural applications, and the overall feasibility of the concept.

Although in theory glass can be endlessly remelted without loss in quality, in practice only a small percentage gets recycled, mainly by the packaging industry. Most of the discarded glass fails to pass the high quality standards of the prevailing glass industry -due to coatings, adhesives, other contaminants or incompatibility of the recipe- and ends up in the landfill. However, employing discarded glass in cast components for building applications can be a way to reintroduce this waste to the supply chain. Such components can tolerate a higher percentage of inclusions, without necessarily compromising their mechanical or aesthetical properties. This paper explores the potential but also the limitations of recycling glass in order to obtain load-bearing components. First, an overview is provided regarding which types of glass reach the recycling plants and the which not, arguing on the reasons behind this selection. Afterwards, a series of experiments is...

Although in theory glass can be endlessly remelted without loss in quality, in practice only a small percentage gets recycled, mainly by the packaging industry. Most of the discarded glass fails to pass the high quality standards of the prevailing glass industry -due to coatings,...

Facades are a crucial interface between exterior and interior conditions and greatly influence the architectural quality of buildings. Glass plays an important role in the building envelope by providing daylight, views and ventilation and hence can contribute significantly to indoor environmental quality and impact occupants’ comfort and well-being. Glass also plays an important role in the energy balance of the envelope and hence in both energy loads and environmental performance of a building. In order to avoid high energy consumption, reduce environmental impact and increase the quality of the space selecting the appropriate size and type of glazing along with the orientation and shading based on the building’s function, the climatic conditions, site and occupants’ needs are a fundamental part of early design stage decisions and are difficult to change later on. The challenge is to improve the building quality by providing a balance between energy efficiency, comfort and saving resources. To reduce energy consumption through glazing taking into account the thermal insulating properties is insufficient, it is also necessary to consider the coatings impact on the physical properties of glass regarding radiation. Coatings are often used to improve the thermal insulation, solar control, acoustic insulation of glazing in order to reduce heat loss, maximize solar gains in winter and minimize it in summer and improve indoor environmental conditions. Multiple configurations of coatings are available on the market to date. The goal of our study is to determine the impact of coated glazing on the energy performance, daylighting and the environmental performance of buildings where occupants spend substantial time inside. This paper incorporates an integrated performance analysis method and presents an energy analysis, daylighting and a life cycle assessment (LCA) study of several coated glazing for patient rooms in Belgium.

Facades are a crucial interface between exterior and interior conditions and greatly influence the architectural quality of buildings. Glass plays an important role in the building envelope by providing daylight, views and ventilation and hence can contribute significantly to indoor environmental quality and impact occupants’ comfort and well-being. Glass also plays an important role in the energy balance of the envelope and hence in both energy loads and environmental performance of a building. In order to avoid high energy consumption, reduce environmental impact and increase the quality of the space selecting the appropriate size and type of glazing along with the orientation and shading based on the building’s function, the climatic conditions, site and occupants’ needs are a fundamental part of early design stage decisions and are difficult to change later on. The challenge is to improve the building quality by providing a balance...

Facades are a crucial interface between exterior and interior conditions and greatly influence the architectural quality of buildings. Glass plays an important role in the building envelope by providing daylight, views and ventilation and hence can...

Curtain wall design commonly uses insulating glass units for vision and spandrel glazing to provide better visual harmonization of building façade glass. Risks with this design approach include higher thermal stresses, especially when low-emissivity coatings are used on insulating glass units in spandrel areas. Ceramic enamel frit – commonly used to opacify spandrel glass – is known to induce a bending strength reduction of up to 50%. The ability of ceramic enamel frit coated glass to resist thermal stress is similarly reduced. Multiple incidences of thermal stress related fracture have occurred with heat-strengthened, ceramic enamel frit opacified spandrel glass. An increased chance of spontaneous breakage, by nickel sulfide inclusions, may occur if ceramic enamel frit opacified spandrel glass is fully-tempered to withstand the thermal stresses that it is exposed to. Silicone spandrel glass coatings have been examined as a solution to prevent the strength reduction in heat-treated glass when ceramic enamel frit is applied as an opacifier. Four-point bending tests were used to investigate the flexural strength of coated heat-strengthened and fully-tempered glass. Ball drop testing was used to investigate the impact resistance of coated fully-tempered glass. Test data shows silicone coatings have no adverse effect on the flexural strength or impact resistance of the substrate and, in some instances, improve it. Therefore, silicone opacifiers do not reduce the resistance to thermal stress of heat-treated glass. These coatings also provide fallout protection in accordance with ASTM C1048 (ASTM, 2012). This suggests using a silicone opacifier on heat-treated spandrel glass could greatly reduce the risk of fracture resulting from thermally induced tensile stress, flexural stress, and impact related glass breakage in addition to reducing risk of injury from fallout if breakage occurs.

Curtain wall design commonly uses insulating glass units for vision and spandrel glazing to provide better visual harmonization of building façade glass. Risks with this design approach include higher thermal stresses, especially when low-emissivity coatings are used on insulating glass units in spandrel areas. Ceramic enamel frit – commonly used to opacify spandrel glass – is known to induce a bending strength reduction of up to 50%. The ability of ceramic enamel frit coated glass to resist thermal stress is similarly reduced. Multiple incidences of thermal stress related fracture have occurred with heat-strengthened, ceramic enamel frit opacified spandrel glass. An increased chance of spontaneous breakage, by nickel sulfide inclusions, may occur if ceramic enamel frit opacified spandrel glass is fully-tempered to withstand the thermal stresses that it is exposed to. Silicone spandrel glass coatings have been examined as a solution to prevent the strength reduction in...

Façades play an important role in the control of energy flow and energy consumption in buildings as they represent the interface between the outdoor environment and the indoor occupied space. The option of regulating internal and external conditions acquires great relevance in new approaches to sustainable building solutions. Studies on climate adaptive façades show a very high potential for improved indoor environmental quality conditions and energy savings by moveable façades. A number of movable façades were realized in the past, but the use of thin glass with a thickness of 0.5 mm to 3 mm opens a brand-new field, that allows for playing with the geometry of the outer skin and the opportunity to make it adaptive by movement. Thin glass requires for curved surfaces in order to gain structural stiffness in static use. In kinetic façades the high flexibility of thin glass allows for new options for changes in size and position by bending of elements rather than implementing hinges in a system of foldable rigid panels. The geometry is based on the known theory of developable surfaces for keeping a low stress-level during movement. This allows for façades created from cold bent thin glass or curved laminated safety glasses produced by laminating of thin glass plies which provide better sealing, greater simplicity in construction and robustness and durability of moveable components which may be actuated autonomously. Some concepts based on the before mentioned theories were created to explain some principles and discuss their principles and applicability.

Façades play an important role in the control of energy flow and energy consumption in buildings as they represent the interface between the outdoor environment and the indoor occupied space. The option of regulating internal and external conditions acquires great relevance in new approaches to sustainable building solutions. Studies on climate adaptive façades show a very high potential for improved indoor environmental quality conditions and energy savings by moveable façades. A number of movable façades were realized in the past, but the use of thin glass with a thickness of 0.5 mm to 3 mm opens a brand-new field, that allows for playing with the geometry of the outer skin and the opportunity to make it adaptive by movement. Thin glass requires for curved surfaces in order to gain structural stiffness in static use. In kinetic façades the high flexibility of thin glass allows for new options for changes in size and position by...

Façades play an important role in the control of energy flow and energy consumption in buildings as they represent the interface between the outdoor environment and the indoor occupied space. The option of regulating internal and external conditions...

The use of ceramic fritted architectural glazing is becoming increasingly popular. “Fritted glass”, which is also known as “enamelled glass”, is defined as glass with a surface covering made of glass frit[1] that is applied by a printing method and fused to the glass substrate at elevated temperatures. The enamel coating may be continuous or consist of a discontinuous pattern such as spots or stripes. Functional thin-film coatings on glass have been used in standard glazing units for many years to improve thermal insulation or for solar control. Specification of light and solar properties for these standard glazing types is well-defined and can be calculated on the basis of the algorithms specified in EN 410:2011 or ISO 9050:2003. This is not the case for glazing that incorporates fritted glass, alone or in combination with functional thin-film coatings. The paper initially describes the different printing options for fritted glass and the fundamental principles of functional thin-film coatings. When glass surfaces are coated with glass frit, it is essential to note that the light-scattering coatings transmit and reflect incident radiation not only directly but also diffusely. The same applies when functional thin-film coatings are combined with frit coatings. Suitable measurement methods to collect the scattered radiation, measured transmittance and reflectance spectra, and the calculation of light and solar properties on the basis of the EN 410:2011 standard are presented. At the same time, the limits of this standard and the need for its extension are demonstrated.

[1] Frit: a durable mixture of glass and ceramic particles, which may act as pigments.

The use of ceramic fritted architectural glazing is becoming increasingly popular. “Fritted glass”, which is also known as “enamelled glass”, is defined as glass with a surface covering made of glass frit[1] that is applied by a printing method and fused to the glass substrate at elevated temperatures. The enamel coating may be continuous or consist of a discontinuous pattern such as spots or stripes. Functional thin-film coatings on glass have been used in standard glazing units for many years to improve thermal insulation or for solar control. Specification of light and solar properties for these standard glazing types is well-defined and can be calculated on the basis of the algorithms specified in EN 410:2011 or ISO 9050:2003. This is not the case for glazing that incorporates fritted glass, alone or in combination with functional thin-film coatings. The paper initially describes the different printing...

The use of ceramic fritted architectural glazing is becoming increasingly popular. “Fritted glass”, which is also known as “enamelled glass”, is defined as glass with a surface covering made of glass frit[1] that is applied by a printing...

Glazing facades generally represent one of the most critical building components, from a structural point of view, since providing a physical separation and barrier for the building occupants. In this regard, especially under the action ofextreme loads, they require specific design concepts voted to protect the building occupants. In this paper, the feasibility and potential of special mechanical connectors interposed at the interface between a given multi-storey primary buildingstructure and the glazing facade are investigated via accurate finite-element models, under the action seismic and explosive loads. Given the case study of a 4-storey steel framed structure enclosed by a glazing curtain wall, both the global and local effects and potential benefits due to additional vibration control systems (VCSs) are preliminary assessed via numerical simulations, giving evidence of the activation—once properly designed—of a distributed-tuned-mass damper (TMD) concept involving the glass facade as a structural component of the 3D building. Differing from traditional TMD applications in civil engineering systems—namely consisting of lumped mass, damping and stiffness terms—these beneficial contributions are derived from the enclosing glass panels. Taking advantage of earlier research studies, in particular, where major efforts have been spent for the potential of visco-elastic VCSs, careful consideration is paid in this paper for the feasibility of elasto-plastic (PL) connectors, giving evidence of their response and effects under both seismic events and explosions. As shown from FE results partly discussed in the paper, the full 3D assembly can take benefit from the proposed design concept, hence suggesting the further development of the explored passive mitigation tool for the protection of the primary building structure.

Glazing facades generally represent one of the most critical building components, from a structural point of view, since providing a physical separation and barrier for the building occupants. In this regard, especially under the action ofextreme loads, they require specific design concepts voted to protect the building occupants. In this paper, the feasibility and potential of special mechanical connectors interposed at the interface between a given multi-storey primary buildingstructure and the glazing facade are investigated via accurate finite-element models, under the action seismic and explosive loads. Given the case study of a 4-storey steel framed structure enclosed by a glazing curtain wall, both the global and local effects and potential benefits due to additional vibration control systems (VCSs) are preliminary assessed via numerical simulations, giving evidence of the activation—once properly designed—of a distributed-tuned-mass damper (TMD) concept...

Glazing facades generally represent one of the most critical building components, from a structural point of view, since providing a physical separation and barrier for the building occupants. In this regard, especially under the action ofextreme loads, they require specific design...

Hybrid & Composite Glass Components

Glass, particularly in architectural design, expresses lightness and modernity. By rising glass surfaces of facades in buildings with high safety requirements, glass works as security glazing. Requirements of security glazing increase constantly. However, single glass panes do not fulfil the demands on these high technology products. Thereby, laminated glass or insulated glass are used to solve problems of the specifications in view of fire, heat, noise, sound and sun protection as well as safety, energy, design or media. The combination of different materials in a composite panel permits the optimisation in consideration of requested structural or mechanical properties. In this case, the lamination of brittle glass with ductile polycarbonate enables innovative composite panels, which extends the range of glazing with security relevant applications. Glass-polycarbonate composite panels are generally defined with two outer glass panes and one or more inner polycarbonate sheets, laminated with polymeric interlayers. The combination of these two materials demonstrates a more efficient alternative to common security glazing. Continuous developments in the field of thin glass result in more and more applications beyond the usage in smartphones or tablets. Large-sized thin glasses with a nominal thickness of 2 mm or less are for some time available and already used in science and technology. Applications of thin glass in the building sector demand to analyse the required material properties and to combine thin glass panes with additional layers due to its low geometrical stiffness. An option for applications of large-sized thin glass panes presents the lamination with polycarbonate. Thin glass substitute the two outer glass panes in glass-polycarbonate composite panels. Therefore, thin glass-polycarbonate composite panels are slighter than common security glazing. Several options for using thin glass in architecture and the lamination with polycarbonate are described as well as the required tests for using as laminated safety glass and security glass with resistance against manual attack.

Glass, particularly in architectural design, expresses lightness and modernity. By rising glass surfaces of facades in buildings with high safety requirements, glass works as security glazing. Requirements of security glazing increase constantly. However, single glass panes do not fulfil the demands on these high technology products. Thereby, laminated glass or insulated glass are used to solve problems of the specifications in view of fire, heat, noise, sound and sun protection as well as safety, energy, design or media. The combination of different materials in a composite panel permits the optimisation in consideration of requested structural or mechanical properties. In this case, the lamination of brittle glass with ductile polycarbonate enables innovative composite panels, which extends the range of glazing with security relevant applications. Glass-polycarbonate composite panels are generally defined with two outer glass panes and one or more inner polycarbonate sheets,...

Glass, particularly in architectural design, expresses lightness and modernity. By rising glass surfaces of facades in buildings with high safety requirements, glass works as security glazing. Requirements of security glazing increase constantly. However, single glass panes do not fulfil the...

The European RFCS project “S+G” has developed innovative steel-glass composite systems for high-performance building skins, meeting requirements of structural and energetic efficiency, as well as aesthetical value and versatility of applications. The aim of the project has been the design, prototype and testing of unitized cells composed by a glass panel and a contouring metallic frame, twisted by cold bending into a hyperbolic paraboloid shape, to be used in free-form curved building façades. To achieve large curvatures while maintaining the stress under the limit strength, very thin glass needs to be used, with a consequent risk of loss of stability. Preliminary investigations have been conducted to evaluate the buckling load in the glass panel and the possible stiffening effect of the contouring metallic frame. Then, accurate FE analyses, accounting for geometric and material nonlinearities, have been used to optimize the design of the unitized cell. Finally, two-steps experimental tests have been performed on full-scale samples. First, the prototypes are cold-twisted, maintaining limited the displacement of the corners, so to avoid buckling. Secondly, out-of-plane loading is applied to simulate wind, snow or man load. Thanks to the curvature, the cells showed very high strength due to the synergetic coupling of steel and glass. Here, we present the experimental and numerical investigations and the main results from full-scale tests. These have been used to refine the FE model, in order to investigate the role of both the interlayer and of the steel-to-glass bonding, and to develop a simplified model for practical design applications.

The European RFCS project “S+G” has developed innovative steel-glass composite systems for high-performance building skins, meeting requirements of structural and energetic efficiency, as well as aesthetical value and versatility of applications. The aim of the project has been the design, prototype and testing of unitized cells composed by a glass panel and a contouring metallic frame, twisted by cold bending into a hyperbolic paraboloid shape, to be used in free-form curved building façades. To achieve large curvatures while maintaining the stress under the limit strength, very thin glass needs to be used, with a consequent risk of loss of stability. Preliminary investigations have been conducted to evaluate the buckling load in the glass panel and the possible stiffening effect of the contouring metallic frame. Then, accurate FE analyses, accounting for geometric and material nonlinearities, have been used to optimize the design of...

The European RFCS project “S+G” has developed innovative steel-glass composite systems for high-performance building skins, meeting requirements of structural and energetic efficiency, as well as aesthetical value and versatility of applications. The...

This paper focuses on a recently developed concept, in which glass is combined with timber to provide post-breakage strength and ductility. This combination allows for good post-breakage performance and overall robustness of timber-glass composite beams and wall elements, which has been reported in several publications. The application of timber-glass elements in practice, however, raises important issues related to structural fire performance. The paper elaborates on this issue and provides general information about the behavior of glass, timber and adhesives at elevated temperatures and under fire conditions. Furthermore, it presents ideas and strategies developed for potential application of timber-glass composites in practical situations. The paper presents also initial results from an on-going research project on fire performance of timber-glass composites.

This paper focuses on a recently developed concept, in which glass is combined with timber to provide post-breakage strength and ductility. This combination allows for good post-breakage performance and overall robustness of timber-glass composite beams and wall elements, which has been reported in several publications. The application of timber-glass elements in practice, however, raises important issues related to structural fire performance. The paper elaborates on this issue and provides general information about the behavior of glass, timber and adhesives at elevated temperatures and under fire conditions. Furthermore, it presents ideas and strategies developed for potential application of timber-glass composites in practical situations. The paper presents also initial results from an on-going research project on fire performance of timber-glass composites.

This paper focuses on a recently developed concept, in which glass is combined with timber to provide post-breakage strength and ductility. This combination allows for good post-breakage performance and overall robustness of timber-glass composite beams...

This paper discusses alternative numerical approaches to the analysis of the structural behaviour of glass beams reinforced with GFRP laminates adhesively bonded, which were calibrated and validated from four-point bending tests available in the literature. For this purpose, smeared crack and damaged plasticity models were used to simulate the non-linear behaviour of glass, available in FEMIX and ABAQUS finite element softwares. The interaction between the materials in the composite beams, using polyurethane or epoxy adhesives, was defined thought different strategies. In all cases it was possible to simulate well the non-linear behaviour of glass-GFRP composite beams. However, while the FEMIX (smeared crack model) results showed greater resemblance to the experimental ones, ABAQUS models, showed to be able to capture in greater detail the effects of cracking in theses structural responses.

This paper discusses alternative numerical approaches to the analysis of the structural behaviour of glass beams reinforced with GFRP laminates adhesively bonded, which were calibrated and validated from four-point bending tests available in the literature. For this purpose, smeared crack and damaged plasticity models were used to simulate the non-linear behaviour of glass, available in FEMIX and ABAQUS finite element softwares. The interaction between the materials in the composite beams, using polyurethane or epoxy adhesives, was defined thought different strategies. In all cases it was possible to simulate well the non-linear behaviour of glass-GFRP composite beams. However, while the FEMIX (smeared crack model) results showed greater resemblance to the experimental ones, ABAQUS models, showed to be able to capture in greater detail the effects of cracking in theses structural responses.

This paper discusses alternative numerical approaches to the analysis of the structural behaviour of glass beams reinforced with GFRP laminates adhesively bonded, which were calibrated and validated from four-point bending tests available in the...

This paper describes the engineering steps taken in order to investigate the potential of glass sandwich elements, made of 2 glass skins separated by a glass core in the form of spacers, as a way to create planar elements with a high stiffness to weight ratio, reducing material consumption in structural glazing applications. The aim is to explore and evaluate the optical quality and the structural performance of those elements. In this research, 7 core topologies are explored in order to define which parameters influence the behaviour of a sandwich structure made completely with glass. From those topologies, one is chosen to be explored further. The said topology is optimised to make the panels more efficient in terms of stiffness and weight reduction. In order to determine the structural behaviour (strength, stiffness, failure modes) of the elements, 4-point bending tests are conducted on 9 specimens in total. Finally, in order to define the aesthetical and structural requirements of such a project, the replacement of the glass floors of the Acropolis Museum in Athens in Greece is used as a case study. The knowledge acquired through this process is used to optimise the panels of the new glass floors taking also into account other parameters related to transparent flooring e.g. optical quality, psychological factors, anti-slip resistance etc

This paper describes the engineering steps taken in order to investigate the potential of glass sandwich elements, made of 2 glass skins separated by a glass core in the form of spacers, as a way to create planar elements with a high stiffness to weight ratio, reducing material consumption in structural glazing applications. The aim is to explore and evaluate the optical quality and the structural performance of those elements. In this research, 7 core topologies are explored in order to define which parameters influence the behaviour of a sandwich structure made completely with glass. From those topologies, one is chosen to be explored further. The said topology is optimised to make the panels more efficient in terms of stiffness and weight reduction. In order to determine the structural behaviour (strength, stiffness, failure modes) of the elements, 4-point bending tests are conducted on 9 specimens in total. Finally, in order to define...

This paper describes the engineering steps taken in order to investigate the potential of glass sandwich elements, made of 2 glass skins separated by a glass core in the form of spacers, as a way to create planar elements with a high stiffness to weight...

An extensive parametric numerical study was performed after completed experimental campaign of timber-glass hybrid walls (TGW and TGWE). 36 timber-glass models (TG) with different outer dimensions were built and analysed using the commercial code SAP2000. Timber frame was modelled using linear beam elements with hinges in all four corners, an IGU was modelled as composite shell and finally a layer of adhesive was modelled with linear and nonlinear springs, which were distributed circumferentially around the edge of IGU and connected onto a timber frame. Normal and shear stiffness coefficients for linear-elastic springs were calculated, while for nonlinear springs a special series of mechanical tests on polyurethane (PU) adhesive was performed since a lack of data available in addition to the desired amount of information needed for the numerical analysis. Uniaxial tension, compression and shear tests were made to obtain the results in form of the load-displacement curve, which presented a direct input for nonlinear normal and shear springs of the mathematical model. For each compression and tension mechanical test three specimens were prepared and tested up to rupture, while a double-lap shear test was conducted using two specimens giving two results each. PU adhesive specimens of the first series had dimensions of 50 mm x 50 mm and thickness of 5,0 mm. Mechanical tests were repeated for two additional thicknesses of PU adhesive, namely 7,0 mm and 9,0 mm. After completed experimental investigation on PU adhesive joint, together 108 numerical models were analysed in SAP2000 with a goal to capture the basic response of mechanically tested timber-glass walls and to determine the stiffness of TGW with different external dimensions. Having the correct information about the stiffness of the single TG shear wall one can calculate the stiffness of the entire timberglass building built with such walls.

An extensive parametric numerical study was performed after completed experimental campaign of timber-glass hybrid walls (TGW and TGWE). 36 timber-glass models (TG) with different outer dimensions were built and analysed using the commercial code SAP2000. Timber frame was modelled using linear beam elements with hinges in all four corners, an IGU was modelled as composite shell and finally a layer of adhesive was modelled with linear and nonlinear springs, which were distributed circumferentially around the edge of IGU and connected onto a timber frame. Normal and shear stiffness coefficients for linear-elastic springs were calculated, while for nonlinear springs a special series of mechanical tests on polyurethane (PU) adhesive was performed since a lack of data available in addition to the desired amount of information needed for the numerical analysis. Uniaxial tension, compression and shear tests were made to obtain the results in form of the load-displacement curve, which...

An extensive parametric numerical study was performed after completed experimental campaign of timber-glass hybrid walls (TGW and TGWE). 36 timber-glass models (TG) with different outer dimensions were built and analysed using the commercial code SAP2000. Timber frame was modelled using linear...

Reinforcement and pre-compression of concrete beams results in a ductile response and allows for the design of structures that are more reliable and efficient. Therefore, this approach has been adapted to structural glass producing reinforced and post-tensioned glass beams. Unbonded tendons in Spannglass Beams are one structural example for realising this idea and are the subject of the presented study. Two individual laminated safety glass packages connected locally by metal dividers characterise these beams. A gap between the packages was used to guide tendons in a either three- or a four-point bending configuration. This eccentric layout allowed for an initial uplift of the cross section and a mechanical pre-compression of the vulnerable glass edge. This was the primary objective during the initial design stage of the concept of Spannglass Beams. However, proving sufficient residual load-bearing capacity is a further requirement to ensure the safety of glass structures and requires additional study. During this stage, a common approach is to evaluate the effect of broken layers in the glass section, which may result in eccentric loading by the tendon and introduce additional bending about the minor axis. Thus, the novel structural design may cause an early (lateral) failure of the structure even during a service load condition. We examined a set of 16 Spannglass Beams with 5.0 mm; 8.1 mm and 10.1 mm post-tensioned cables in an experimental study during four-point bending. Additionally, four un-reinforced specimens and four beams with untensioned tendons were tested. The paper includes a testing method to evaluate theresidual load-bearing behaviour. First, the specimens were loaded in bending, after which a single glass layer was damaged manually by a hammer and a chisel. Finally, the assembly was left for 24 hours before taking a next step to damage a consecutive layer. In this manner, it was possible to evaluate the residual load-bearing behaviour in terms of residual service-life as a function of damage scenario and load. Additionally, the crack pattern after each step, the evolvement of the deflection and the change in cable load were analysed before the final failure modes were characterised. This report aims to describe the effects of post-tensioning on the residual load-bearing capacity of glass beams. It was possible to influence the structural response considerably by reinforcing and post-tensioning glass beams. Due to excessive lateral deflection, an additional cable load reduced the residual service-life. However, the number of connectors in Spannglass Beams determined the shape during bending with a special focus on the buckling length and thus contributed to increasing the service-life as a major parameter during design. Finally, we derived structural recommendations for a future design of effective glass beams in facades, roofs or even “floating” glass bridges.

Reinforcement and pre-compression of concrete beams results in a ductile response and allows for the design of structures that are more reliable and efficient. Therefore, this approach has been adapted to structural glass producing reinforced and post-tensioned glass beams. Unbonded tendons in Spannglass Beams are one structural example for realising this idea and are the subject of the presented study. Two individual laminated safety glass packages connected locally by metal dividers characterise these beams. A gap between the packages was used to guide tendons in a either three- or a four-point bending configuration. This eccentric layout allowed for an initial uplift of the cross section and a mechanical pre-compression of the vulnerable glass edge. This was the primary objective during the initial design stage of the concept of Spannglass Beams. However, proving sufficient residual load-bearing capacity is a further requirement to ensure the safety of glass...

Reinforcement and pre-compression of concrete beams results in a ductile response and allows for the design of structures that are more reliable and efficient. Therefore, this approach has been adapted to structural glass producing reinforced and post-tensioned glass beams. Unbonded tendons in...

In contemporary architecture, glass is more and more applied not only to make up the cladding of the building, but also for structural members such as beams and façade fins. The trend to increase the scale of these structural entities makes it increasingly structurally efficient to apply statically indeterminate beam systems. For these systems to be approved, contemporary building codes require them to provide structural safety on an element and system level. Therefore, a lot of hybrid glass beam concepts, in which glass is combined with another material that provides post-fracture capacity, were developed and investigated. Among others, reinforced glass beams have experimentally proven their feasibility for statically determinate (element safety) and indeterminate (system safety) support conditions by providing significant post-fracture capacity, ductility, plastic hinge formation and load redistribution capacity. However, system safety can also benefit from the effects of membrane action, which can result in yet higher post-fracture performance. Moreover, the latter can make a significant contribution to the robustness of a beam system when an accidental event occurs such as collapse of one of the supports. This paper presents experimental test results of statically indeterminate five-point bending tests with clamping end-supports on twelve 4.3 m long stainless steel reinforced beam specimens in which the horizontal membrane forces are assessed. Two series of tests were performed, with and without intermediate support, for two types of beams with varying reinforcement percentage (i.e. solid and hollow profile reinforcement). During the tests, significant compressive as well as tensile membrane action was observed. The effects of the latter on the loadcarrying behaviour is discussed by comparing the load-deflection diagrams with those of similar reinforced glass beam systems without clamped external supports. From this comparison, it is concluded that membrane action provides significant contribution to the load-carrying behaviour of such beam systems. Significantly higher post-fracture capacities can be achieved for both reinforcement sections and both types of tests. It is concluded that membrane action can be incorporated in design, which will lead to more economical, slender and more transparent reinforced glass beam systems.

In contemporary architecture, glass is more and more applied not only to make up the cladding of the building, but also for structural members such as beams and façade fins. The trend to increase the scale of these structural entities makes it increasingly structurally efficient to apply statically indeterminate beam systems. For these systems to be approved, contemporary building codes require them to provide structural safety on an element and system level. Therefore, a lot of hybrid glass beam concepts, in which glass is combined with another material that provides post-fracture capacity, were developed and investigated. Among others, reinforced glass beams have experimentally proven their feasibility for statically determinate (element safety) and indeterminate (system safety) support conditions by providing significant post-fracture capacity, ductility, plastic hinge formation and load redistribution capacity. However, system safety can also benefit from the...

In contemporary architecture, glass is more and more applied not only to make up the cladding of the building, but also for structural members such as beams and façade fins. The trend to increase the scale of these structural entities makes it increasingly structurally efficient to apply...

The current rise of wooden constructions, which is encouraged by a strong trend towards sustainability of our buildings, also engenders innovation in facade design and materials. Timber-glass composite elements are a novel interpretation of the structural sealant glazing concept aiming at a reduction of the carbon footprint of facades by using materials from renewable resources. Already available facade systems based on the principle of timber-glass composite construction are applied in curtain walls, which is a rather conventional way. This paper assesses the feasibility of cold bended timberglass composite elements to widen the scope of possible applications to curved or freeform surfaces such as timber grid shells. Cold bending appears an efficient way to adopt the flat element to a non-regularly shaped substructure. The twisting from an initial undeformed to a deflected state leads to permanent stresses in the glass as well as in the adhesive joint, the adapter and the screwed connection. Numerical models of a rectangular and a square-shaped timber-glass composite element help to understand the mechanical reactions in the individual components and the joint. The virtual components are deflected on one corner while the other three remain in plane. The cold bending of such elements is additionally assessed in life-size experiments. Shape and size correlate to those used in the numerical models to enable a validation of the virtual model. The derived stresses and time-depended deformations of the deflected test specimens yield a better understanding of the structural behavior and design of timber-glass composite elements.

The current rise of wooden constructions, which is encouraged by a strong trend towards sustainability of our buildings, also engenders innovation in facade design and materials. Timber-glass composite elements are a novel interpretation of the structural sealant glazing concept aiming at a reduction of the carbon footprint of facades by using materials from renewable resources. Already available facade systems based on the principle of timber-glass composite construction are applied in curtain walls, which is a rather conventional way. This paper assesses the feasibility of cold bended timberglass composite elements to widen the scope of possible applications to curved or freeform surfaces such as timber grid shells. Cold bending appears an efficient way to adopt the flat element to a non-regularly shaped substructure. The twisting from an initial undeformed to a deflected state leads to permanent stresses in the glass as well as in the adhesive joint, the adapter...

The current rise of wooden constructions, which is encouraged by a strong trend towards sustainability of our buildings, also engenders innovation in facade design and materials. Timber-glass composite elements are a novel interpretation of the structural sealant glazing concept aiming...

Insulating Glass Units

Glass is an increasingly used material in construction and buildings. Despite its large application as load-bearing construction material, several aspects related to safe and optimal design are still under investigation and exploration, towards the full implementation of standardized rules of practical use. One of the main concerns in the design of this typically tensile brittle material is the rational estimation of static fatigue phenomena, under the effects of multiple design loads. In this paper, following earlier efforts, careful consideration is paid to the ultimate resistance verification (ULS) of structural glass elements under a combination of variable loads with specific duration. The ULS resistance assessment is carried out for double insulated glass units, being representative of large number of glass applications in buildings, and requiring specific design assumptions due to their intrinsic features.

Glass is an increasingly used material in construction and buildings. Despite its large application as load-bearing construction material, several aspects related to safe and optimal design are still under investigation and exploration, towards the full implementation of standardized rules of practical use. One of the main concerns in the design of this typically tensile brittle material is the rational estimation of static fatigue phenomena, under the effects of multiple design loads. In this paper, following earlier efforts, careful consideration is paid to the ultimate resistance verification (ULS) of structural glass elements under a combination of variable loads with specific duration. The ULS resistance assessment is carried out for double insulated glass units, being representative of large number of glass applications in buildings, and requiring specific design assumptions due to their intrinsic features.

Glass is an increasingly used material in construction and buildings. Despite its large application as load-bearing construction material, several aspects related to safe and optimal design are still under investigation and exploration, towards the full implementation of standardized...

Insulated glass units (IGUs) are employed in modern buildings as a substitute for monolithic glass to reduce heat loss through windows. In the past decades, the pursuit of higher aesthetic design drives glazed products evolving from conventionally flat into more creative and dynamic curved shapes. The call for curved IGUs brings up a series of challenges, and one remarkable issue is the determination of load sharing and glass stress when evaluating its structural performance. Even though many national codes worldwide have established mature design approaches for load sharing of flat IGUs panels, such design approaches can scarcely be found for curved IGUs due to geometry complexity. In this paper, the author will use an FEA tool along with automatic iteration scripts to carry out a sensitivity study on the internal climatic pressure of cylindrically curved IGUs, considering a series of geometrical variables. The paper aims to evaluate the relationships between the internal pressure and the geometrical parameters of curved IGUs and normalize all these parameters into a dimensionless chart.

Insulated glass units (IGUs) are employed in modern buildings as a substitute for monolithic glass to reduce heat loss through windows. In the past decades, the pursuit of higher aesthetic design drives glazed products evolving from conventionally flat into more creative and dynamic curved shapes. The call for curved IGUs brings up a series of challenges, and one remarkable issue is the determination of load sharing and glass stress when evaluating its structural performance. Even though many national codes worldwide have established mature design approaches for load sharing of flat IGUs panels, such design approaches can scarcely be found for curved IGUs due to geometry complexity. In this paper, the author will use an FEA tool along with automatic iteration scripts to carry out a sensitivity study on the internal climatic pressure of cylindrically curved IGUs, considering a series of geometrical variables. The paper aims to evaluate the relationships between the...

Insulated glass units (IGUs) are employed in modern buildings as a substitute for monolithic glass to reduce heat loss through windows. In the past decades, the pursuit of higher aesthetic design drives glazed products evolving from conventionally flat into more creative and dynamic curved...

Joints, Fixings & Adhesives

The brittle material behaviour of glass means the inefficiency of contemporary mechanical connection technologies hampers the exploitation of full potential of glass for delivering energy efficient buildings. This paper presents the results of an experimental investigation of the use of adhesively bonded Glass Fibre Reinforced Polymer (GFRP) strips as a mean improving strength and ductility of bolted joints in glass. The peak load and the post-peak ductility of GFRP reinforced joints in annealed glass in double-lap tension joint configurations were experimentally investigated and compared with equivalent unstrengthened reference bolted joints in annealed glass and fully-toughened glass. The results show that the peak load of the reinforced joints in annealed glass increased up to 250%. The reinforced joints also showed a notable ductility compared to the reference annealed glass and fully-toughened glass test specimens.

The brittle material behaviour of glass means the inefficiency of contemporary mechanical connection technologies hampers the exploitation of full potential of glass for delivering energy efficient buildings. This paper presents the results of an experimental investigation of the use of adhesively bonded Glass Fibre Reinforced Polymer (GFRP) strips as a mean improving strength and ductility of bolted joints in glass. The peak load and the post-peak ductility of GFRP reinforced joints in annealed glass in double-lap tension joint configurations were experimentally investigated and compared with equivalent unstrengthened reference bolted joints in annealed glass and fully-toughened glass. The results show that the peak load of the reinforced joints in annealed glass increased up to 250%. The reinforced joints also showed a notable ductility compared to the reference annealed glass and fully-toughened glass test specimens.

The brittle material behaviour of glass means the inefficiency of contemporary mechanical connection technologies hampers the exploitation of full potential of glass for delivering energy efficient buildings. This paper presents the results of an experimental investigation of the use of...

The German research team FABIG develops a bioenergy building skin including modules of glass which contain a liquid medium processing biomass. Inside the facade modules, load-bearing adhesives were applied that are subject to permanent water exposure. Water is known as a major hazard for adhesives because water molecules diffuse into the adhesive polymer matrix and into the interface between adhesive and substrate. As a result, material characteristics as well as the adhesion properties may change significantly. Additionally, the adhesive is exposed to conventional aging in building skin as the temperature ranges between -20°C and +80°C. This paper focuses on the effect of water on load-bearing adhesives in a bioenergy facade. It evaluates potential adhesives for permanent hydrothermal application. The paper introduces water as a key aging medium. Furthermore, it describes the construction of an innovative flat plate photobioreactor as an example for load-bearing adhesives under permanent hydrothermal treatment. The conditions inside the photobioreactor, which lead to particular mechanical, physical and chemical loads for constructive elements in comparison with conventional facade systems are presented. The main part describes the results of experimental tensile tests on the adhesive short-term behavior considering temperature conditioning and chemical treatment with substances emerging from bio-processing like storing in acid, base and hydrogen peroxide solution. The paper concludes with an outlook on future research work of the team including ARUP Deutschland GmbH (Berlin, Germany), ADCO Technik GmbH (Rostock, Germany), SSC GmbH (Hamburg, Germany) and Technische Universität Dresden (Dresden, Germany).

The German research team FABIG develops a bioenergy building skin including modules of glass which contain a liquid medium processing biomass. Inside the facade modules, load-bearing adhesives were applied that are subject to permanent water exposure. Water is known as a major hazard for adhesives because water molecules diffuse into the adhesive polymer matrix and into the interface between adhesive and substrate. As a result, material characteristics as well as the adhesion properties may change significantly. Additionally, the adhesive is exposed to conventional aging in building skin as the temperature ranges between -20°C and +80°C. This paper focuses on the effect of water on load-bearing adhesives in a bioenergy facade. It evaluates potential adhesives for permanent hydrothermal application. The paper introduces water as a key aging medium. Furthermore, it describes the construction of an innovative flat plate photobioreactor as an example for load-bearing...

The German research team FABIG develops a bioenergy building skin including modules of glass which contain a liquid medium processing biomass. Inside the facade modules, load-bearing adhesives were applied that are subject to permanent water exposure. Water is known as a major hazard for...

Adhesive connections offer a number of benefits in structural applications, especially in the case of brittle adherends such as glass. There, a multitude of materials can be used to provide structural bonding between glass and/or metal components, giving evidence of different mechanical behaviours as well as structural performances. This paper reports on a Finite Element numerical investigation carried out on small-scale adhesive joint specimens. Taking advantage of a past experimental study performed at CTU in Prague - focused on both material tests and small-scale adhesive connections subjected to shear loading - the numerical modelling approach is validated by taking into account a selection of shear tests on glass-to-steel adhesive joints. The typical specimen is composed of two glass plates bonded to two steel plates with a gap between them and four adhesive joints per one specimens. Finite Element numerical analyses are presented, as obtained from full 3D solid models representative of the specimens components. While careful consideration is spent for the mechanical description of materials, a key role is indeed assigned to cohesive surface interactions, being representative of any possible damage occurring at the interface between the adhesive layers and the bonded substrates. The sensitivity of FE results to input parameters responsible of damage initiation and propagation is discussed, based on past experimental observations.

Adhesive connections offer a number of benefits in structural applications, especially in the case of brittle adherends such as glass. There, a multitude of materials can be used to provide structural bonding between glass and/or metal components, giving evidence of different mechanical behaviours as well as structural performances. This paper reports on a Finite Element numerical investigation carried out on small-scale adhesive joint specimens. Taking advantage of a past experimental study performed at CTU in Prague - focused on both material tests and small-scale adhesive connections subjected to shear loading - the numerical modelling approach is validated by taking into account a selection of shear tests on glass-to-steel adhesive joints. The typical specimen is composed of two glass plates bonded to two steel plates with a gap between them and four adhesive joints per one specimens. Finite Element numerical analyses are presented, as obtained from full 3D solid models...

Adhesive connections offer a number of benefits in structural applications, especially in the case of brittle adherends such as glass. There, a multitude of materials can be used to provide structural bonding between glass and/or metal components, giving evidence of different mechanical...

Historically, silicone joint dimensioning is calculated with a simplified equation implemented in various standards for structural glazing. This equation assumes homogeneous stress distribution along the sealant bite whilst high local stress peaks, structure deformation or material ageing are included in a global safety factor. Safeguards such as a maximum authorized deflection (1%) and aspect ratio to respect (between 1 and 3) have been given to ensure the validity of the used equations. However new trends in commercial buildings such as the use of large dimensions glass panes or stronger engineering performance requirements such as high windloads above 5000Pa lead to the non-respect of these guidelines and the impossibility to use the simplified equation. An improved mathematical relationship making a direct correspondence between a joint included in a façade system and the behavior of a test piece was recently proposed by the authors. The goal of this article is to further validate the proposed relationship by confronting predictions with physical measurements on various test samples and the results from FEA modeling. The domain of validity of the simplified equation and the improved equation will be developed.

Historically, silicone joint dimensioning is calculated with a simplified equation implemented in various standards for structural glazing. This equation assumes homogeneous stress distribution along the sealant bite whilst high local stress peaks, structure deformation or material ageing are included in a global safety factor. Safeguards such as a maximum authorized deflection (1%) and aspect ratio to respect (between 1 and 3) have been given to ensure the validity of the used equations. However new trends in commercial buildings such as the use of large dimensions glass panes or stronger engineering performance requirements such as high windloads above 5000Pa lead to the non-respect of these guidelines and the impossibility to use the simplified equation. An improved mathematical relationship making a direct correspondence between a joint included in a façade system and the behavior of a test piece was recently proposed by the authors....

Historically, silicone joint dimensioning is calculated with a simplified equation implemented in various standards for structural glazing. This equation assumes homogeneous stress distribution along the sealant bite whilst high local stress peaks,...

In the design of blast resistant glazing systems, gluing the laminate glass to the window frame with a structural adhesive is an attractive option to maintain it attached to the frame while, because the large deflection of the broken laminate, it could potentially escape from a mechanical fixing. Actually, it does not exist a simple method that provides guidelines to the facade maker to design a joint that will resist to a blast. The complexity to develop such a method is due to 1) the blast load is time dependent and the phase shift between the external load and the natural mode of vibration of the pane must be included in the model 2) modeling the deformation of a laminated glass after breakage of glass plies is complex. The intend of this study is not to propose the most accurate description of both the laminate and the joint deformation under a blast load but to identify which assumptions could be possibly made to simplify the problem and make possible the derivation of a simplified joint dimensioning method.

In the design of blast resistant glazing systems, gluing the laminate glass to the window frame with a structural adhesive is an attractive option to maintain it attached to the frame while, because the large deflection of the broken laminate, it could potentially escape from a mechanical fixing. Actually, it does not exist a simple method that provides guidelines to the facade maker to design a joint that will resist to a blast. The complexity to develop such a method is due to 1) the blast load is time dependent and the phase shift between the external load and the natural mode of vibration of the pane must be included in the model 2) modeling the deformation of a laminated glass after breakage of glass plies is complex. The intend of this study is not to propose the most accurate description of both the laminate and the joint deformation under a blast load but to identify which assumptions could be possibly made to simplify the problem...

In the design of blast resistant glazing systems, gluing the laminate glass to the window frame with a structural adhesive is an attractive option to maintain it attached to the frame while, because the large deflection of the broken laminate, it could...

The demand for transparent but robust designs in architecture is still enormous. One of the most complex points of the application of glass is the use of efficient and appropriate connection details. The article examines a modular glass system about its architectural possibilities with a special focus on the connection methodology. We constructed a 2 x 2 x 1m prototype of specially laminated glass sheets with integrated connection details in the framework of a Master of Science programme on digital fabrication with support from Seele and Bischoff Glastechnik, which was also featured in two public exhibitions at TU Munich and the House of Architecture in Munich. The design potential is investigated using parametric geometrical modelling as well as FEM sensitivity analysis. At the interface between the architect and the engineer, the consequences of the FEM analysis are discussed reflecting the influence of the chosen connection to the peak stresses within the structure and expected deflections. A typical part of the examined structure is prepared as an FEA-model. The abstraction of the connection details within the model allows a more in-depth analysis of the load transmissions between the glass panes using non-linear contact effects as well as the rheological behaviour of the interlayer material. The examined structure was designed for application in small-scale architectural design. Beside the design, and analysis of the structure fabrication and installation aspects and their consequences to the design is explained in detail. Unique aspects of this article are new possibility to build transparent and efficient façade systems that can be flexibly adapted to possible areas of application due to the parametrically supported design processes. In addition to the design process, the direct interaction between the architect and the engineer was also able to consider the aspects of the data exchange regarding detail development. The article concludes with a description of further development for full-scale architectural applications and the necessary research.

The demand for transparent but robust designs in architecture is still enormous. One of the most complex points of the application of glass is the use of efficient and appropriate connection details. The article examines a modular glass system about its architectural possibilities with a special focus on the connection methodology. We constructed a 2 x 2 x 1m prototype of specially laminated glass sheets with integrated connection details in the framework of a Master of Science programme on digital fabrication with support from Seele and Bischoff Glastechnik, which was also featured in two public exhibitions at TU Munich and the House of Architecture in Munich. The design potential is investigated using parametric geometrical modelling as well as FEM sensitivity analysis. At the interface between the architect and the engineer, the consequences of the FEM analysis are discussed reflecting the influence of the chosen connection to the peak stresses within the structure and...

The demand for transparent but robust designs in architecture is still enormous. One of the most complex points of the application of glass is the use of efficient and appropriate connection details. The article examines a modular glass system about its architectural possibilities with a...

The connections between glass components are very critical aspects of structural glass design. Laminated steel-to-glass connections have recently been developed that combine high strength and transparency. This work focuses on the Transparent Structural Silicone Adhesive (TSSA), produced by Dow Corning. TSSA is typically used for the realization of circular point connections on the glass surface. An alternative approach of using TSSA is considered in this study, by laminating stainless steel connectors on the edge of the glass. These connections are experimentally and numerically investigated. The edge bonded specimens are tested in shear and the stress distribution of the adhesive is analyzed by means of a three-dimensional finite element model. The distribution of stresses in the adhesive is non-linear showing significant stress peaks towards the free edges of the adhesive. A parametric study is conducted to relate the magnitude of the shear stress peaks and bending stresses with the eccentricity of the applied load. The occurrence of failure at lower engineering stresses than the ones recorded for circular point connections is explained using the theory of bending-shear interaction laws. Based on these failure criteria, shear stress peaks that occur due to the eccentricity of the applied load have an important influence on the global resistance of the connection.

The connections between glass components are very critical aspects of structural glass design. Laminated steel-to-glass connections have recently been developed that combine high strength and transparency. This work focuses on the Transparent Structural Silicone Adhesive (TSSA), produced by Dow Corning. TSSA is typically used for the realization of circular point connections on the glass surface. An alternative approach of using TSSA is considered in this study, by laminating stainless steel connectors on the edge of the glass. These connections are experimentally and numerically investigated. The edge bonded specimens are tested in shear and the stress distribution of the adhesive is analyzed by means of a three-dimensional finite element model. The distribution of stresses in the adhesive is non-linear showing significant stress peaks towards the free edges of the adhesive. A parametric study is conducted to relate the magnitude of the...

The connections between glass components are very critical aspects of structural glass design. Laminated steel-to-glass connections have recently been developed that combine high strength and transparency. This work focuses on the Transparent Structural...

The current European standard for dimensioning silicone adhesive joints in structural glazing applications is defined in the ETAG 002. Although there are several decades of field experience with this standard it still has some major limitations and mainly uses an empirical concept based on an average force by area tension engineering approach. In addition there are a number of other restrictions for example the limitation of specific substrates and rectangular shaped joints with defined aspect ratios as well as the exclusion of joints with non-coplanar surfaces. The presented investigations are based on a combined numerical and experimental concept and demonstrate that appropriately designed elastic adhesive joints with complex geometries excluded by common standards can be evaluated and validated in a systematic and reliable way. The experimental test may easily be combined with well-established and proven aging test schemes, for which long-term reliable field experience is available. In addition any desired safety factor can be added.

The current European standard for dimensioning silicone adhesive joints in structural glazing applications is defined in the ETAG 002. Although there are several decades of field experience with this standard it still has some major limitations and mainly uses an empirical concept based on an average force by area tension engineering approach. In addition there are a number of other restrictions for example the limitation of specific substrates and rectangular shaped joints with defined aspect ratios as well as the exclusion of joints with non-coplanar surfaces. The presented investigations are based on a combined numerical and experimental concept and demonstrate that appropriately designed elastic adhesive joints with complex geometries excluded by common standards can be evaluated and validated in a systematic and reliable way. The experimental test may easily be combined with well-established and proven aging test schemes, for which long-term reliable field experience is...

The current European standard for dimensioning silicone adhesive joints in structural glazing applications is defined in the ETAG 002. Although there are several decades of field experience with this standard it still has some major limitations and mainly uses an empirical concept based on an...

Glass is an indispensable material in the building industry. The combination of transparency, strength and durability makes it to an unparalleled and desirable material. The technology additive manufacturing (AM) has a potential in the building industry, based on a relatively small amount of repetitions of particular building components and the tendency of applying technology innovations for buildings. Therefore, there is an interest for additive manufacturing with glass. This paper presents and summarizes the results of the preliminary research regarding additive manufacturing of glass components for joining methods for flat glass structures. Different types of glass (borosilicate glass, quartz glass and soda lime silicate glass) are discussed. Experimental investigations of joints are intended to illustrate the performance and potential of AM glass components in case of structural use. Load bearing tests were carried out to quantify the strength and load bearing capacity level of an AM structural component. The thermal residual stresses were examined by photo-elastic tests with polarized lights and scattered light method. The investigations show in principle that load transfer via fused glass joints is possible. The performed research activity is a first step towards the Additive Manufacturing of glass structures on flat glass.

Glass is an indispensable material in the building industry. The combination of transparency, strength and durability makes it to an unparalleled and desirable material. The technology additive manufacturing (AM) has a potential in the building industry, based on a relatively small amount of repetitions of particular building components and the tendency of applying technology innovations for buildings. Therefore, there is an interest for additive manufacturing with glass. This paper presents and summarizes the results of the preliminary research regarding additive manufacturing of glass components for joining methods for flat glass structures. Different types of glass (borosilicate glass, quartz glass and soda lime silicate glass) are discussed. Experimental investigations of joints are intended to illustrate the performance and potential of AM glass components in case of structural use. Load bearing tests were carried out to quantify the strength and load bearing capacity level...

Glass is an indispensable material in the building industry. The combination of transparency, strength and durability makes it to an unparalleled and desirable material. The technology additive manufacturing (AM) has a potential in the building industry, based on a relatively small amount of...

A trend towards adhesive connections instead of mechanical ones can be observed for transparent facades in recent years. Furthermore, research efforts are made to increase the efficiency regarding material use by designing systems with composite structural behavior. In this article, experimental and numerical results obtained for linear structural silicone joints between glass and stainless steel substrates, investigated separately under tensile and under shear loading, are discussed. The two selected adhesives, Dow Corning® 993 and Sikasil® SG-550, are approved for structural sealant glazing systems and are planned to be used within a novel concept for façade elements with composite structural behavior, consisting of a glass pane and a filigree metal framing. For an adhesive joint with prismatic geometry, the influence of different lengths, widths and thicknesses of the joint on its mechanical performance is assessed experimentally under tensile loading, while under shear loading only different thicknesses are investigated. Both under tensile and under shear loading, a dependency of the failure engineering stresses on the joint thickness is noticed. In a second step, the suitability of selected hyperelastic models is assessed for predicting the load versus displacement behavior of the investigated linear adhesive joints. The parameters required for these models are determined based on uniaxial tensile tests on dumbbell specimens.

A trend towards adhesive connections instead of mechanical ones can be observed for transparent facades in recent years. Furthermore, research efforts are made to increase the efficiency regarding material use by designing systems with composite structural behavior. In this article, experimental and numerical results obtained for linear structural silicone joints between glass and stainless steel substrates, investigated separately under tensile and under shear loading, are discussed. The two selected adhesives, Dow Corning® 993 and Sikasil® SG-550, are approved for structural sealant glazing systems and are planned to be used within a novel concept for façade elements with composite structural behavior, consisting of a glass pane and a filigree metal framing. For an adhesive joint with prismatic geometry, the influence of different lengths, widths and thicknesses of the joint on its mechanical performance is...

A trend towards adhesive connections instead of mechanical ones can be observed for transparent facades in recent years. Furthermore, research efforts are made to increase the efficiency regarding material use by designing systems with composite...

Cavitation in rubber-like materials describes sudden void growth of an initially voided material under hydrostatic tension until the material fails. To study the cavitation effect numerically, classical cavitation criteria are coupled with a continuum damage formulation of a Neo-Hookean material. A cavitation criterion defines a failure surface in threedimensional stress or strain space, which represents the onset of excessive void growth and therefore the strong degradation of the bulk modulus. To account for this special case of material softening, a novel continuum damage formulation at finite strains is presented, where the initially constant bulk modulus of a hyperelastic material is reduced after satisfying a cavitation criterion. Since this formulation leads to an abrupt damage initiation, additionally a continuously volumetric damage formulation is proposed and compared with it. Therefore, novel void growth criteria are developed, which describe the cavitation effect even under smallest volumetric strains. For numerical validation, a single element test is simulated under hydrostatic tension. Furthermore, pancake tests are numerically analysed. The results with regard on the chosen cavitation criterion and the abrupt/continuously damage formulation are compared with each other analysing TSSA.

Cavitation in rubber-like materials describes sudden void growth of an initially voided material under hydrostatic tension until the material fails. To study the cavitation effect numerically, classical cavitation criteria are coupled with a continuum damage formulation of a Neo-Hookean material. A cavitation criterion defines a failure surface in threedimensional stress or strain space, which represents the onset of excessive void growth and therefore the strong degradation of the bulk modulus. To account for this special case of material softening, a novel continuum damage formulation at finite strains is presented, where the initially constant bulk modulus of a hyperelastic material is reduced after satisfying a cavitation criterion. Since this formulation leads to an abrupt damage initiation, additionally a continuously volumetric damage formulation is proposed and compared with it. Therefore, novel void growth criteria are developed, which describe the cavitation effect even...

Cavitation in rubber-like materials describes sudden void growth of an initially voided material under hydrostatic tension until the material fails. To study the cavitation effect numerically, classical cavitation criteria are coupled with a continuum damage formulation of a Neo-Hookean...

The main advantage of solid bricks over hollow blocks is substantially higher compressive strength. On the other hand, solid bricks have much higher thermal conductivity, which would lead to major heat loss when used for exterior walls. Masonry pillars and walls are usually loaded by compression and/or bending resulting from the eccentricity of vertical load or wind load. In case of solid glass bricks, compressive strength is about ten times higher than tension strength therefore the limiting factor of the glass masonry is tensile stress resulting from the bending. Whether compared to ceramic or concrete bricks masonry, the glass bricks have a smooth and non-absorbent surface and the adhesion of the mortar to the glass surface is the critical parameter. Presented paper is focused on the experimental investigation of mortar applicable for glass brick masonry with regard to possible use for supporting brick walls or columns. Shear, compression and adhesion tests have been recently performed. Shear and adhesion resistance and failure modes of brick bed joint were determined during series of tests using various mortar composition, two types of surface treatment and different thickness of the mortar joint. Significant influence of the joint thickness on the resistance was found. The compression tests were performed on two small pillars to determine the compression resistance and failure mode of glass bricks walls and pillars. In parallel to these tests, several small-scale tests have been performed to determine of flexural and compressive strength of hardened mortar.

The main advantage of solid bricks over hollow blocks is substantially higher compressive strength. On the other hand, solid bricks have much higher thermal conductivity, which would lead to major heat loss when used for exterior walls. Masonry pillars and walls are usually loaded by compression and/or bending resulting from the eccentricity of vertical load or wind load. In case of solid glass bricks, compressive strength is about ten times higher than tension strength therefore the limiting factor of the glass masonry is tensile stress resulting from the bending. Whether compared to ceramic or concrete bricks masonry, the glass bricks have a smooth and non-absorbent surface and the adhesion of the mortar to the glass surface is the critical parameter. Presented paper is focused on the experimental investigation of mortar applicable for glass brick masonry with regard to possible use for supporting brick walls or columns. Shear, compression and adhesion tests have been recently...

The main advantage of solid bricks over hollow blocks is substantially higher compressive strength. On the other hand, solid bricks have much higher thermal conductivity, which would lead to major heat loss when used for exterior walls. Masonry pillars and walls are usually loaded by...

Steel-to-glass laminated connections, which have recently been developed, limit stress intensifications on the glass and combine strength and transparency. Transparent Structural Silicone Adhesive (TSSA) connections have been used in several projects worldwide; however, the hyperelastic and viscoelastic nature of the material has to date not been fully investigated. In this work, the first objective is to investigate the mechanical response of TSSA connections under static and cyclic loading by means of experimental tests. Firstly, the shear behaviour of TSSA circular connections is characterized by means of monotonic and cyclic loading tests. The adhesive exhibits significant stress-softening under repeated cycles that becomes more severe as the maximum load increases. Secondly, TSSA circular connections are subjected to monotonic and cyclic tensile loading of increasing maximum load. The way whitening propagates on the adhesive surface shows some consistency comparing the cases of static and cyclic loading. The second objective is to analytically describe the deformation behaviour of the adhesive based on hyperelastic prediction models. Uniaxial and biaxial tension tests are combined with the simple shear tests, for the material characterization of TSSA. The hyperelastic material parameters are calibrated by a simultaneous multi-experiment-data-fit based on the nonlinear least squares optimization method. The softening behaviour observed in shear tests is modeled based on a simplified pseudo-elastic damage model proposed by Ogden–Roxburgh. A first attempt is also made to model the actual softening response of the adhesive. A less conservative approach proposed by Guo, also based on the theory of pseudo-elasticity, proved to give a good approximation of the actual cyclic response of the adhesive.

Steel-to-glass laminated connections, which have recently been developed, limit stress intensifications on the glass and combine strength and transparency. Transparent Structural Silicone Adhesive (TSSA) connections have been used in several projects worldwide; however, the hyperelastic and viscoelastic nature of the material has to date not been fully investigated. In this work, the first objective is to investigate the mechanical response of TSSA connections under static and cyclic loading by means of experimental tests. Firstly, the shear behaviour of TSSA circular connections is characterized by means of monotonic and cyclic loading tests. The adhesive exhibits significant stress-softening under repeated cycles that becomes more severe as the maximum load increases. Secondly, TSSA circular connections are subjected to monotonic and cyclic tensile loading of increasing maximum load. The way whitening propagates on the adhesive surface shows some consistency comparing the cases...

Steel-to-glass laminated connections, which have recently been developed, limit stress intensifications on the glass and combine strength and transparency. Transparent Structural Silicone Adhesive (TSSA) connections have been used in several projects worldwide; however, the hyperelastic and...

This paper investigates the use of bolted and brittle/ductile adhesive connections in glass structures. Two benchmark designs of shear connections are introduced and tested experimentally in quasi-static tensile tests. The designs consist oftempered glass and aluminium substrates while steel splices are used for the load application. In addition, material characterisation testing for the glass and the adhesive is performed and the outputs are used for the numerical simulation of the same joints. Pressure-sensitive, plasticity and failure models are introduced and calibrated to accurately capture the behaviour of the adhesives. Good agreement between the experimental observations and numerical predictions is achieved. The results show that both types of adhesive joints outperform bolted joints while counter-intuitively the lower strength ductile adhesive achieves consistently higher joint strength compared to the brittle adhesive. The numerical analyses highlight that while brittle adhesive joints fail once the fracture strain of the adhesive has been reached, while for ductile adhesives an extensive plastic zone develops near the areas of stress concentrations thereby delaying the damage initiation.

This paper investigates the use of bolted and brittle/ductile adhesive connections in glass structures. Two benchmark designs of shear connections are introduced and tested experimentally in quasi-static tensile tests. The designs consist oftempered glass and aluminium substrates while steel splices are used for the load application. In addition, material characterisation testing for the glass and the adhesive is performed and the outputs are used for the numerical simulation of the same joints. Pressure-sensitive, plasticity and failure models are introduced and calibrated to accurately capture the behaviour of the adhesives. Good agreement between the experimental observations and numerical predictions is achieved. The results show that both types of adhesive joints outperform bolted joints while counter-intuitively the lower strength ductile adhesive achieves consistently higher joint strength compared to the brittle adhesive. The numerical analyses highlight that while...

This paper investigates the use of bolted and brittle/ductile adhesive connections in glass structures. Two benchmark designs of shear connections are introduced and tested experimentally in quasi-static tensile tests. The designs consist oftempered glass and aluminium substrates while...

Structural sealant glazing systems (SSGS), currently also known as bonded glass, for façades originated over 50 years ago. Although a lot of new developments were introduced and essential experience was gained, the design of the continuous adhesive glass-metal connections used in conventional SSGS did not undergo significant changes ever since. To optimise the design of such connections and to enable the development of new and innovative concepts of adhesive connections in building construction, fundamental research on the structural performance of adhesive glass-metal connections is, therefore, inevitable. In this research, the focus lies on the mechanical behaviour of continuous adhesive glass-steel connections under cyclic loading to which these elements are subjected on a daily basis, e.g. wind, or possibly subjected during their lifetime, e.g. earthquakes. The aim was, by means of experimental testing, to compare the structural response of a continuous adhesive glass-cold-formed (stainless) steel connection using a conventional structural silicone under cyclic loading with the mechanical behaviour under monotonic loading. The experimental results revealed the presence of progressive cyclic softening in the continuous adhesive glass-steel connections. This can mainly be attributed to the appreciable change in mechanical properties of the structural silicone resulting from the maximum deformation value prior to cyclic loading, i.e. the Mullins effect. Based on the experimental results, a simplified analytical model was elaborated and (partially) validated. The effect of cyclic loading is an issue that has to be accounted for within further optimisation of glass-metal connections using rubber-like adhesives, e.g. structural silicones.

Structural sealant glazing systems (SSGS), currently also known as bonded glass, for façades originated over 50 years ago. Although a lot of new developments were introduced and essential experience was gained, the design of the continuous adhesive glass-metal connections used in conventional SSGS did not undergo significant changes ever since. To optimise the design of such connections and to enable the development of new and innovative concepts of adhesive connections in building construction, fundamental research on the structural performance of adhesive glass-metal connections is, therefore, inevitable. In this research, the focus lies on the mechanical behaviour of continuous adhesive glass-steel connections under cyclic loading to which these elements are subjected on a daily basis, e.g. wind, or possibly subjected during their lifetime, e.g. earthquakes. The aim was, by means of experimental testing, to compare the structural response of a continuous adhesive...

Structural sealant glazing systems (SSGS), currently also known as bonded glass, for façades originated over 50 years ago. Although a lot of new developments were introduced and essential experience was gained, the design of the continuous adhesive glass-metal connections used in conventional...

Laminated Glass & Interlayer Properties

Laminated glass, composed by glass plies sandwiching polymeric interlayers, can provide a safe post-glass breakage response, in compliance with the fail-safe approach used in the structural design. In fact, when glass breaks, shards remain attached to the polymer, preventing danger from falling materials and imparting a "tension stiffening" effect to the interlayer, so that the broken panel maintains a certain residual load-bearing capacity. Here, a homogenized approach is presented to describe the mechanical properties of broken heat-treated laminated glass under tensile stresses. The model accounts for the stress diffusion from the delaminated zones, where shards are bridged by the interlayer-ligament only, to the regions where glass is bonded to the interlayer. The model provides a simple but accurate estimate of the effective tensile properties of the cracked laminate. Here, the influence of the interlayer thickness, the size of the glass shards and the glass-polymer delamination on the post-critical response is accurately investigated, and analytical results are compared with numerical ones. The obtained expression for the tensile modulus is used to predict, in more general terms, the response of cracked laminated glass under in-plane and out-of-plane bending. In both cases, a key point is the correct evaluation of the tension stiffening in the polymeric interlayer due to the adhesion with the glass shards.

Laminated glass, composed by glass plies sandwiching polymeric interlayers, can provide a safe post-glass breakage response, in compliance with the fail-safe approach used in the structural design. In fact, when glass breaks, shards remain attached to the polymer, preventing danger from falling materials and imparting a "tension stiffening" effect to the interlayer, so that the broken panel maintains a certain residual load-bearing capacity. Here, a homogenized approach is presented to describe the mechanical properties of broken heat-treated laminated glass under tensile stresses. The model accounts for the stress diffusion from the delaminated zones, where shards are bridged by the interlayer-ligament only, to the regions where glass is bonded to the interlayer. The model provides a simple but accurate estimate of the effective tensile properties of the cracked laminate. Here, the influence of the interlayer thickness, the size of the glass shards and the glass-polymer...

Laminated glass, composed by glass plies sandwiching polymeric interlayers, can provide a safe post-glass breakage response, in compliance with the fail-safe approach used in the structural design. In fact, when glass breaks, shards remain attached to the polymer, preventing danger...

Looking at a current architecture, there are many examples of glass load bearing structures such as beams, panes, balustrades, columns or even stairs. These elements are mostly made of laminated glass panels. Panels are bonded together with polymer interlayer significantly influencing a shear forces transfer between them. There is still overall lack of knowledge in the task of shear forces transfer between these panels. It principally depends on the polymer stiffness, which is affected by an ambient temperature, humidity and load duration. Civil engineers currently tend to design laminated glass members on the safe side, generally not taking laminated panels interaction provided by the interlayer into account. This approach leads to uneconomical and robust glass bearing members significantly preventing the use of laminated glass more extensively. There are many polymer interlayers made for structural laminated glass applications available on a market. Most of them differ in stiffness and other important properties therefore these must be experimentally examined to design safer and more economical laminated glass members. This paper is focused on the shear modulus of PVB (polyvinyl-buthyral) and SentryGlasÒ (ionoplast) experimental investigations as a function of temperature and loading ratio. It is possible to find out these functions by static creep or relaxation tests as well as by dynamic mechanical thermal analysis-DMTA. A lot of DMTA experiments in shear with the aforementioned interlayers in various loading conditions have been performed in order to determine their shear stiffness. It also enables to identify their Prony parameters as a part of the next survey. Experimentally verified common polymer interlayer stiffness helps engineers to design safer and cheaper glass constructions. This is the way how to extend the use of laminated glass in a current architecture.

Looking at a current architecture, there are many examples of glass load bearing structures such as beams, panes, balustrades, columns or even stairs. These elements are mostly made of laminated glass panels. Panels are bonded together with polymer interlayer significantly influencing a shear forces transfer between them. There is still overall lack of knowledge in the task of shear forces transfer between these panels. It principally depends on the polymer stiffness, which is affected by an ambient temperature, humidity and load duration. Civil engineers currently tend to design laminated glass members on the safe side, generally not taking laminated panels interaction provided by the interlayer into account. This approach leads to uneconomical and robust glass bearing members significantly preventing the use of laminated glass more extensively. There are many polymer interlayers made for structural laminated glass applications available on a market. Most of them differ in...

Looking at a current architecture, there are many examples of glass load bearing structures such as beams, panes, balustrades, columns or even stairs. These elements are mostly made of laminated glass panels. Panels are bonded together with polymer interlayer significantly influencing a shear...

Slender glass panels are widely used as storefronts and indoor separating walls in shopping malls and public buildings. To ensure that the design and construction is technically safe for general use and that it meets current and accepted technical standards, in-situ testing is required by the building administrator or authorities. A case study was performed of an indoor glass lantern in a public building made from slender two-side supported glass panels with a complex geometry. It provides structural assessments and results of in-situ experiments including static loading and soft body impact test. Results from numerical simulations of impact loading on the glass panels complementing the experimental results are also presented. The in-situ testing proved that the structural design meets current standards regarding the static loading. The soft body impact test proved the safety of the intact panel and the panel with one ply deliberately broken. The numerical study showed that, for a more complicated geometry, the stress distribution can dramatically change over time and that stress concentrations can develop at certain locations at a late stage in the impact history.

Slender glass panels are widely used as storefronts and indoor separating walls in shopping malls and public buildings. To ensure that the design and construction is technically safe for general use and that it meets current and accepted technical standards, in-situ testing is required by the building administrator or authorities. A case study was performed of an indoor glass lantern in a public building made from slender two-side supported glass panels with a complex geometry. It provides structural assessments and results of in-situ experiments including static loading and soft body impact test. Results from numerical simulations of impact loading on the glass panels complementing the experimental results are also presented. The in-situ testing proved that the structural design meets current standards regarding the static loading. The soft body impact test proved the safety of the intact panel and the panel with one ply deliberately...

Slender glass panels are widely used as storefronts and indoor separating walls in shopping malls and public buildings. To ensure that the design and construction is technically safe for general use and that it meets current and accepted technical...

Laminated glass provides safety in an impact or explosion event by way of a polymer interlayer to which glass fragments adhere upon fracture. The mechanical deformation of the interlayer defines how the impact energy can be absorbed to prevent calamities by flying glass debris, penetration of a blast wave, lacerations, etc. The PVB interlayer used in safety glass shows highly nonlinear viscoelastic material behaviour, with a great sensitivity to temperature and deformation rate. Although various material models for PVB can be found in literature, few publications discuss the full range of its mechanical behaviour and none are found to describe a material model that is valid in a wide range of deformation rates and up to high elongations. Such material model is necessary for the numerical study of the post-fracture response in a dynamic event. The article describes the mechanical behaviour of PVB interlayer and the constitutive models by which the polymer can be represented under different load cases. Tensile experiments of Saflex® PVB are presented for a wide range of deformation rates and up to tearing of the specimens. Subsequently, a method to calibrate a hyper-viscoelastic material model for the interlayer by numerically simulating the tensile tests is developed. The resulting material models are valid up to the tearing strain of the interlayer and are accurate within a specified range of deformation rates and temperatures.

Laminated glass provides safety in an impact or explosion event by way of a polymer interlayer to which glass fragments adhere upon fracture. The mechanical deformation of the interlayer defines how the impact energy can be absorbed to prevent calamities by flying glass debris, penetration of a blast wave, lacerations, etc. The PVB interlayer used in safety glass shows highly nonlinear viscoelastic material behaviour, with a great sensitivity to temperature and deformation rate. Although various material models for PVB can be found in literature, few publications discuss the full range of its mechanical behaviour and none are found to describe a material model that is valid in a wide range of deformation rates and up to high elongations. Such material model is necessary for the numerical study of the post-fracture response in a dynamic event. The article describes the mechanical behaviour of PVB interlayer and the constitutive models by which the polymer can be represented under...

Laminated glass provides safety in an impact or explosion event by way of a polymer interlayer to which glass fragments adhere upon fracture. The mechanical deformation of the interlayer defines how the impact energy can be absorbed to prevent calamities by flying glass debris, penetration of...

In the long run laminated glass interlayers are sensitive to weather conditions. Several studies have been carried out that aim at understanding the consequences of moisture and solar radiation on adhesion to glass and on the mechanical response of the composite pane. In particular, solar radiation seems to produce the strongest effects on the bulk properties of PVB, modifying the coupling capability of laminated glass plates exposed to the direct sunlight. Such problem has been already studied by the authors via dynamic tests on small laminated glass specimens subjected to artificial UV light; however, due to the methodology of these mechanical tests, it was not possible to repeat the experiment on the same specimens subjected to different exposition times, and it was not possible to investigate the laws of accumulation of the consequences of weathering actions. In fact, solar radiation could produce different effects on the structure of material, but only superimposed consequences can be observed. In order to better understand the time progression of the phenomenon, creep tests were performed on laminated glass beams subjected to four-point bending; the specimens were tested in correspondence of definite time intervals of UV exposure. The total amount of time will be defined according to the observed variation of test results with respect to the total exposure. The effects of UV radiation are highlighted directly comparing the displacement history diagram and successively evaluated analyzing the mechanical parameters that describe the rheological behavior.

In the long run laminated glass interlayers are sensitive to weather conditions. Several studies have been carried out that aim at understanding the consequences of moisture and solar radiation on adhesion to glass and on the mechanical response of the composite pane. In particular, solar radiation seems to produce the strongest effects on the bulk properties of PVB, modifying the coupling capability of laminated glass plates exposed to the direct sunlight. Such problem has been already studied by the authors via dynamic tests on small laminated glass specimens subjected to artificial UV light; however, due to the methodology of these mechanical tests, it was not possible to repeat the experiment on the same specimens subjected to different exposition times, and it was not possible to investigate the laws of accumulation of the consequences of weathering actions. In fact, solar radiation could produce different effects on the structure of...

In the long run laminated glass interlayers are sensitive to weather conditions. Several studies have been carried out that aim at understanding the consequences of moisture and solar radiation on adhesion to glass and on the mechanical response of the...

The subject area "structural strength of materials" is defined generally as а complex of strength characteristics of materials and structural elements, obtained under special mechanical tests. It is shown that these tests should take into account not only the physical and mechanical properties of the material, but technology, blank processing, sphere of application, the influence of shape and sizes of elements as well as of their specific loading and operating conditions. Methods for evaluating the structural strength of glass as a linearly elastic material with high sensitivity to technological defects and operational damage are discussed in the paper. Some results of the study of the strength of elements of architectural and bulletproof laminated glass are given. The sizes of technological defects such as cracks in large-sized building elements are determined on the basis of the results of tests of sheet glass plates on bending. The bending strength of sheet float glass with a thickness up to 10 mm reinforced with modification of the glass surface using various industrial technologies is considered. Some methods and results of experimental study the features of the change in the strength and rigidity of laminated armored glass under multiple ballistic tests are also presented.

The subject area "structural strength of materials" is defined generally as а complex of strength characteristics of materials and structural elements, obtained under special mechanical tests. It is shown that these tests should take into account not only the physical and mechanical properties of the material, but technology, blank processing, sphere of application, the influence of shape and sizes of elements as well as of their specific loading and operating conditions. Methods for evaluating the structural strength of glass as a linearly elastic material with high sensitivity to technological defects and operational damage are discussed in the paper. Some results of the study of the strength of elements of architectural and bulletproof laminated glass are given. The sizes of technological defects such as cracks in large-sized building elements are determined on the basis of the results of tests of sheet glass plates on bending. The bending strength of sheet float glass with a...

The subject area "structural strength of materials" is defined generally as а complex of strength characteristics of materials and structural elements, obtained under special mechanical tests. It is shown that these tests should take into account not only the physical and mechanical...

Engineers and designers are using glass in increasingly demanding applications such as stairs, floors, and bridges, large minimally supported facades and overhead glazing. The use of laminated glass in structural applications has become more recognized and preferred as safer choice to monolithic tempered or heat strengthen glass. Structural interlayers are stiff interlayers that increase the strength of the laminated glass enabling the glass structure to handle higher loads with thinner glass. The use of structural interlayers enables laminated glass use in the most demanding applications giving architects and engineers greater design freedom. Today engineers and designers have options when choosing a structural interlayer for their application, Stiff PVB or ionoplast interlayer. Both interlayers provide improved post breakage strength and structural benefits; however, some significant differences in properties that affect the final laminate performance exist. Applications that require higher temperatures above 30⁰C and/or long load duration, ionoplast interlayers perform the best. When the load duration or design temperatures are lower stiff PVB is a good choice. From the laminators perspective properties such as yield and final laminate quality are important considerations as well. There are differences between the structural interlayers seen during the lamination process that can influence lamination quality and yields. Stiff PVB process similar to standard PVB while standard ionoplast interlayers require some special processing. This may present a challenge for the laminators. Recent improvements in ionoplast interlayer technology now enable ionoplast to be laminated more similar to PVB giving laminators and engineers the best of both.

Engineers and designers are using glass in increasingly demanding applications such as stairs, floors, and bridges, large minimally supported facades and overhead glazing. The use of laminated glass in structural applications has become more recognized and preferred as safer choice to monolithic tempered or heat strengthen glass. Structural interlayers are stiff interlayers that increase the strength of the laminated glass enabling the glass structure to handle higher loads with thinner glass. The use of structural interlayers enables laminated glass use in the most demanding applications giving architects and engineers greater design freedom. Today engineers and designers have options when choosing a structural interlayer for their application, Stiff PVB or ionoplast interlayer. Both interlayers provide improved post breakage strength and structural benefits; however, some significant differences in properties that affect the final laminate performance...

Engineers and designers are using glass in increasingly demanding applications such as stairs, floors, and bridges, large minimally supported facades and overhead glazing. The use of laminated glass in structural applications has become more recognized and preferred as safer choice to...

Modern façade glass elements need to meet high standards of solar performance, as well as thermal insulation, while maintaining transparency requirements. These requirements are key to provide comfort for the building users and minimize energy requirements for heating and/or cooling. In today’s urban environment, likely additional requirements for reflectivity, glare and acoustic performance are in place. Advanced glass coatings have come a long way in meeting many of the requirements, and have developed to the extent that further development provides diminishing returns, either in their own performance, or in combination with other coatings. There are applications in the architectural space that have relied on other technologies to meet the requirements if the use of coatings was somehow restricted, e.g. warm bent glass, applications where edge deletion is not acceptable, or where coatings interfere with electromagnetic signal transmission. An example of such a technology are solar absorbing PVB interlayers for laminated safety glass. This paper illustrates how coating technologies and solar absorbing PVB interlayers can be combined to optimize façade glass performance.

Modern façade glass elements need to meet high standards of solar performance, as well as thermal insulation, while maintaining transparency requirements. These requirements are key to provide comfort for the building users and minimize energy requirements for heating and/or cooling. In today’s urban environment, likely additional requirements for reflectivity, glare and acoustic performance are in place. Advanced glass coatings have come a long way in meeting many of the requirements, and have developed to the extent that further development provides diminishing returns, either in their own performance, or in combination with other coatings. There are applications in the architectural space that have relied on other technologies to meet the requirements if the use of coatings was somehow restricted, e.g. warm bent glass, applications where edge deletion is not acceptable, or where coatings interfere with electromagnetic signal transmission. An example of such a technology are...

Modern façade glass elements need to meet high standards of solar performance, as well as thermal insulation, while maintaining transparency requirements. These requirements are key to provide comfort for the building users and minimize energy requirements for heating and/or cooling. In...

Laboratory testing data concerning the full sized laminated glass panel with different glass make-ups under impact is limited. An experimental investigation on the impact resistance of LG panels under hard body impact is reported in this paper. A test approach namely, mean minimum breakage velocity approach, is adopted to capture the minimum impact energy that triggers each glass breakage. The crack morphology of glass panels is firstly investigated. Results indicate that the intersection angle of the radial crack edges increases when the strengthening level of glass decreases. The impact resistance is then revealed by investigating the effects caused by three design variables, i.e., the glass types, interlayer thickness and interlayer types. It reveals that the configuration with inner HS glass and outer FT glass panel can provide better impact resistance, and performs better in keeping initial stiffness under repeated impacts with higher impact velocity. In the contrast, placing HS glass in the both side may weaken the impact resistance. A 1.52 mm PVB interlayer can provide better impact resistance and higher initial stiffness when compared to a thicker interlayer, it is more likely to produce stiffness degradation between consecutive breakages as well. The difference of SGP LG and PVB LG in MMBV is found to be negligible, however, SGP LG exhibits evidently higher initial pre breakage stiffness and remains greater post breakage strength.

Laboratory testing data concerning the full sized laminated glass panel with different glass make-ups under impact is limited. An experimental investigation on the impact resistance of LG panels under hard body impact is reported in this paper. A test approach namely, mean minimum breakage velocity approach, is adopted to capture the minimum impact energy that triggers each glass breakage. The crack morphology of glass panels is firstly investigated. Results indicate that the intersection angle of the radial crack edges increases when the strengthening level of glass decreases. The impact resistance is then revealed by investigating the effects caused by three design variables, i.e., the glass types, interlayer thickness and interlayer types. It reveals that the configuration with inner HS glass and outer FT glass panel can provide better impact resistance, and performs better in keeping initial stiffness under repeated impacts with higher...

Laboratory testing data concerning the full sized laminated glass panel with different glass make-ups under impact is limited. An experimental investigation on the impact resistance of LG panels under hard body impact is reported in this paper. A test...

Laminated glass fulfills the demands on safety and security in transparent structural elements used in architecture and other fields of engineering. It can be constructed as forced-entry, bullet, or blast resistant. The basic three-layer configuration consists of two glass panes connected with a polymer or ionomer interlayer; the advanced products contain also other layers. The foil ensures shear coupling and provides post-breakage resistance and damping. For the design of laminated glass structures and their analysis, knowledge of mechanical properties of interlayers is essential. In numerical simulations, the interlayer is most typically described by the generalized Maxwell chain ‒ a classical viscoelastic model which can capture the time/temperature-dependent response of polymers under shear. Its parameters can be found for common interlayer types in the literature. However, they differ even for the same material, because of a slightly different content of additives, different test setups, and different data processing procedures. In this contribution, the dependence of the response of a laminated glass element on the material parameters of the polymer interlayer is studied by means of numerical modelling and experiments. Two examples are shown and discussed, i.e., quasi-static analysis of a simply-supported beam and modal analysis of a free-free beam. Numerical predictions are obtained by a layer-wise model based on the finite element method. These predictions are validated against the detailed experimental data. We demonstrate that using the Maxwell model parameters from the literature determined even for the same material type but not for the concrete foil may lead to unrealistic predictions.

Laminated glass fulfills the demands on safety and security in transparent structural elements used in architecture and other fields of engineering. It can be constructed as forced-entry, bullet, or blast resistant. The basic three-layer configuration consists of two glass panes connected with a polymer or ionomer interlayer; the advanced products contain also other layers. The foil ensures shear coupling and provides post-breakage resistance and damping. For the design of laminated glass structures and their analysis, knowledge of mechanical properties of interlayers is essential. In numerical simulations, the interlayer is most typically described by the generalized Maxwell chain ‒ a classical viscoelastic model which can capture the time/temperature-dependent response of polymers under shear. Its parameters can be found for common interlayer types in the literature. However, they differ even for the same material, because of a slightly...

Laminated glass fulfills the demands on safety and security in transparent structural elements used in architecture and other fields of engineering. It can be constructed as forced-entry, bullet, or blast resistant. The basic three-layer configuration...

This abstract relates to the recent publication [Viverge K., Boutin C., Sallet F. : Model of highly contrasted plates versus experiments on laminated glass, IJSS, 102-103, 238-258 (2016)]. This contribution provides a synthetic analytic formulation describing the behaviour of laminated glass under static and dynamic loadings, that is validated by experiments. We only give here a synoptic overview and for in depth reading one may refer to the above mentioned publication.

As the laminated glass is made of stiff glass layers pasted with soft viscoelastic interlayers a specific model is established to account for the high contrast of mechanical properties. The effective plate model is derived from (i) the constitutive laws of the materials combined with (ii) an asymptotic expansion formulation and (iii) the appropriate scaling of the stiffness contrast. The different regimes of behaviour are clearly specified, according to the mechanical and geometrical parameters of the layers, and to the loading. The analysis evidences the enriched kinematics of highly contrasted plates and yields to an analytic bi-torsor representation that encompasses (i) the shear related to the sliding within the PVB, (ii) the local bending of each glass layer, and (iii) global bending of the whole laminate. Hence, the model can degenerate in either Reissner–Mindlin plate or shear-bending plate model, depending on the parameters of the constituents. In general it results in a tri-Laplacian formulation that help in understanding the behaviour and enables to derive analytical solutions under basic loadings. Furthermore, the theory applies to viscoelastic layers as PVB in laminated glass. This enriched plate model is validated through experiments conducted on two layers laminated glass with viscoelastic PVB interlayers. The theoretical result stating that the principle of time-temperature superposition of the PVB also applies, with the same time factor to the laminated glass, is observed experimentally. In addition, bending creep tests evidence the theoretically predicted transition from the (quasi-) monolithic behaviour at short time to the (quasi-) bi-layers behaviour at long time. The theoretical results describing the influence of both the temperature and frequency are also in good agreement with the experimental data. To conclude, the proposed model provides a simple easy-to-use theoretical framework for engineering purposes. For instance, it allows simple comparisons of the performances - in time and temperature - of laminated glasses made with different polymeric layers. In addition, the presented analytical results are suitable for determining the optimal design of structural elements made of laminated glass. Applications to the assessment or the improvement of the sound attenuation by laminated glass may also be considered.

This abstract relates to the recent publication [Viverge K., Boutin C., Sallet F. : Model of highly contrasted plates versus experiments on laminated glass, IJSS, 102-103, 238-258 (2016)]. This contribution provides a synthetic analytic formulation describing the behaviour of laminated glass under static and dynamic loadings, that is validated by experiments. We only give here a synoptic overview and for in depth reading one may refer to the above mentioned publication.

As the laminated glass is made of stiff glass layers pasted with soft viscoelastic interlayers a specific model is established to account for the high contrast of mechanical properties. The effective plate model is derived from (i) the constitutive laws of the materials combined with (ii) an asymptotic expansion formulation and (iii) the appropriate scaling of the stiffness contrast. The different regimes of behaviour are clearly specified, according to the mechanical and geometrical...

Polymeric interlayers used in laminated glass show viscoelastic material behaviour. Therefore, the precise design of laminated glass structures is dependent on temperature and the load duration. For the determination of the abovementioned material behaviour of the interlayers different small and big scale test setups exist. One of these tests is the torsional test in which the shear modulus of the interlayer can be calculated from measured data during a relaxation test. In this test, a laminated glass plate is conditioned at a certain temperature of interest and then isothermally twisted to a specific angle, thereby the resulting torsional moment at the support is measured over a time span. With this data, it is possible to calculate the corresponding shear modulus of the interlayer. There are a lot of parameters and boundary conditions with potential influence on the test and the results (e.g. accuracy of the thickness of the glass plates and interlayer, accuracy of the twist-angle, clamping of the laminated glass). Based on already conducted torsional tests at the ‘University of German Armed Forces Munich’ a Finite Element Model was implemented. In a sensitivity analysis (Finite-Element-Analysis using ANSYS® V17.2) the influences and the interdependencies of the parameters and boundary conditions of the test setup were determined. The results of the analyses can be used to get an understanding of the significance of the measured and calculated values for the shear modulus of the interlayer using a torsional test. Furthermore, the results can help to optimize the torsional test. Moreover, the torsional test results were compared to small scale test results from a Dynamical Mechanical Thermal Analysis, which exposes small scale test specimen to a steady state oscillation at different frequencies and temperatures.

Polymeric interlayers used in laminated glass show viscoelastic material behaviour. Therefore, the precise design of laminated glass structures is dependent on temperature and the load duration. For the determination of the abovementioned material behaviour of the interlayers different small and big scale test setups exist. One of these tests is the torsional test in which the shear modulus of the interlayer can be calculated from measured data during a relaxation test. In this test, a laminated glass plate is conditioned at a certain temperature of interest and then isothermally twisted to a specific angle, thereby the resulting torsional moment at the support is measured over a time span. With this data, it is possible to calculate the corresponding shear modulus of the interlayer. There are a lot of parameters and boundary conditions with potential influence on the test and the results (e.g. accuracy of the thickness of the glass plates and interlayer, accuracy of the...

Polymeric interlayers used in laminated glass show viscoelastic material behaviour. Therefore, the precise design of laminated glass structures is dependent on temperature and the load duration. For the determination of the abovementioned material behaviour of the interlayers different small...

Laminated safety glass has become an indispensable component in building construction, automotive and solar industry. It consists of at least two glass panes, that are laminated together with a polymeric interlayer. Mechanically speaking, the polymeric interlayer enables a shear transfer between the two glass panes. Here, the difficulty lies in the understanding of the real shear transmission. On the one hand, polymeric interlayers show a time dependent material behaviour, which can be described with a ‘Prony-series’ in the linear viscoelastic area. On the other hand, polymeric interlayers show a temperature dependent material behaviour. Hence, a Prony-series is only valid for one specific temperature. However, since relaxation is based on molecular movements and rearrangement processes, which can be thermally activated, an increase in temperature leads to an acceleration of the relaxation process. The time-temperature correlation can be taken into account by means of a ‘Time-Temperature-Superposition-Principle’ (TTSP). The relaxation curve of a thermorheologically simple material shifts solely horizontal along the time axis due to temperature changes, while its shape remains constant. Mathematically, this means, that all relaxation times of the Prony-series are multiplied by the same shift factor aT. Recent research of the authors shows, that some polymeric interlayers don’t follow a simple TTSP. The experimental identification through ‘Dynamical-Mechanical-Thermal-Analysis’ as well as ‘Differential Scanning Caliometry’ and numerical incorporation of this thermorheologically complex material behaviour into state-of-the-art Finite-Element-Software will be investigated on the example of ‘Ethylene-vinyl acetate’ in the following paper.

Laminated safety glass has become an indispensable component in building construction, automotive and solar industry. It consists of at least two glass panes, that are laminated together with a polymeric interlayer. Mechanically speaking, the polymeric interlayer enables a shear transfer between the two glass panes. Here, the difficulty lies in the understanding of the real shear transmission. On the one hand, polymeric interlayers show a time dependent material behaviour, which can be described with a ‘Prony-series’ in the linear viscoelastic area. On the other hand, polymeric interlayers show a temperature dependent material behaviour. Hence, a Prony-series is only valid for one specific temperature. However, since relaxation is based on molecular movements and rearrangement processes, which can be thermally activated, an increase in temperature leads to an acceleration of the relaxation process. The time-temperature correlation can be taken into account by...

Laminated safety glass has become an indispensable component in building construction, automotive and solar industry. It consists of at least two glass panes, that are laminated together with a polymeric interlayer. Mechanically speaking, the polymeric interlayer enables a shear transfer...

Numerical Modeling & Experimental Validation

Modern building envelopes are typically high-technological systems that need to meet strict requirements regarding architectural intent, structural capacity, energy-efficiency and durability. The study presented in this paper is based on recent research performed at the Glass & Façade Technology Research Group (University of Cambridge) that investigates high-performance engineered unitised systems as an alternative to traditional curtain-walls for building facades. The proposed unitised systems has a sandwich design made of two outer glass face sheets separated by, and bonded to, glass fibre-reinforced polymer (GFRP) pultruded profiles. This arrangement results in a lightweight and slim structure that could potentially provide high structural and thermal performances. Results discussed in this paper constitute a preliminary outcome of an extended investigation aimed to assess and compare, by means of Finite Element (FE) numerical simulations, the thermal and structural performances of novel frame-integrated (GFRP-glass) sandwich systems and traditional non-integrated frame curtain wall systems. The reported FE results, as shown, give evidence of the potential of the novel design concept, with improved thermal and structural performances compared to traditional non-integrated systems (up to +10% and +15%, respectively).

Modern building envelopes are typically high-technological systems that need to meet strict requirements regarding architectural intent, structural capacity, energy-efficiency and durability. The study presented in this paper is based on recent research performed at the Glass & Façade Technology Research Group (University of Cambridge) that investigates high-performance engineered unitised systems as an alternative to traditional curtain-walls for building facades. The proposed unitised systems has a sandwich design made of two outer glass face sheets separated by, and bonded to, glass fibre-reinforced polymer (GFRP) pultruded profiles. This arrangement results in a lightweight and slim structure that could potentially provide high structural and thermal performances. Results discussed in this paper constitute a preliminary outcome of an extended investigation aimed to assess and compare, by means of Finite Element (FE) numerical simulations, the thermal and structural...

Modern building envelopes are typically high-technological systems that need to meet strict requirements regarding architectural intent, structural capacity, energy-efficiency and durability. The study presented in this paper is based on recent research performed at the Glass & Façade...

In this paper, careful consideration is paid for structural glass elements under fire loading. In particular, a thermo-mechanical Finite Element (FE) numerical investigation is carried out in ABAQUS on small-scale structural glass elements exposed to fire. Taking advantage of past literature efforts, major thermal effects on the material properties are taken into account in the form of key input parameters for numerical simulations. Further validation of the so calibrated FE models is then carried out towards past small-scale experimental fire tests on monolithic glass panels. A sensitivity FE study is hence proposed, giving evidence of major influencing parameters on the thermo-mechanical performance of the same structural glass elements, including variations in the fire exposure, thermal-to-mechanical loading ratio, geometrical and mechanical features of the specimens.

In this paper, careful consideration is paid for structural glass elements under fire loading. In particular, a thermo-mechanical Finite Element (FE) numerical investigation is carried out in ABAQUS on small-scale structural glass elements exposed to fire. Taking advantage of past literature efforts, major thermal effects on the material properties are taken into account in the form of key input parameters for numerical simulations. Further validation of the so calibrated FE models is then carried out towards past small-scale experimental fire tests on monolithic glass panels. A sensitivity FE study is hence proposed, giving evidence of major influencing parameters on the thermo-mechanical performance of the same structural glass elements, including variations in the fire exposure, thermal-to-mechanical loading ratio, geometrical and mechanical features of the specimens.

In this paper, careful consideration is paid for structural glass elements under fire loading. In particular, a thermo-mechanical Finite Element (FE) numerical investigation is carried out in ABAQUS on small-scale structural glass elements exposed to fire. Taking advantage of past literature...

Wind induced pressure is a major design consideration for glazing design. However, the effects of façade geometry and urban terrain on wind loading are often difficult to quantify without costly and time-consuming wind tunnel testing. Accurate 3-dimensional data, covering most major cities, is becoming increasingly accessible, and such models are ideal to support numerical modelling of environmental effects on the built environment, especially if such modelling attempts to capture the geometric effects of the cityscape. A new methodology to assess the effects of wind loads on the structural strength of glass using transient, geometrically non-linear analyses and improved glass failure prediction models is presented. A description is provided for both the calculation of wind-induced façade loads, and the development and employment of a finite element (FE) solver to model façade performance.

Wind induced pressure is a major design consideration for glazing design. However, the effects of façade geometry and urban terrain on wind loading are often difficult to quantify without costly and time-consuming wind tunnel testing. Accurate 3-dimensional data, covering most major cities, is becoming increasingly accessible, and such models are ideal to support numerical modelling of environmental effects on the built environment, especially if such modelling attempts to capture the geometric effects of the cityscape. A new methodology to assess the effects of wind loads on the structural strength of glass using transient, geometrically non-linear analyses and improved glass failure prediction models is presented. A description is provided for both the calculation of wind-induced façade loads, and the development and employment of a finite element (FE) solver to model façade performance.

Wind induced pressure is a major design consideration for glazing design. However, the effects of façade geometry and urban terrain on wind loading are often difficult to quantify without costly and time-consuming wind tunnel testing. Accurate 3-dimensional data, covering most major...

The growth of the industrial production generates a high volume of waste materials. These products have a significant impact on the environment. Therefore, the valorization of industrial wastes, especially those produced in huge quantities, is an important social and ecological issue. Waste reuse and recycling could help to develop new products and aggregate value to materials that would have been previously discarded. Furthermore, it could reduce the consumption of natural resources and pollution. Blast furnace slag and fly ash are waste materials largely used in concrete production, mainly as an aggregate, and road construction, as porous asphalt and in other contexts. These wastes contain many elements that are also present in typical glass formulas, such as CaO, SiO2, Al2O3, and Fe2O3. However, these elements are highly refractory, and their presence in complex compositions leads to a high tendency to crystallize and to high working temperatures. For this reason, it is a challenge to get transparent materials at reasonable temperatures from these waste products. Glass is a material that allows large amounts of various elements in solution, and is suitable for assimilating the complex materials in its compositions. In this work, we produced transparent glass samples incorporating amounts up to 35% (in weight) of blast furnace slag or fly ash. The compositions were adjusted in order to allow for chemically durable glasses in relatively low melting temperature: the samples were successfully submitted to water durability tests and were obtained in melting temperatures between 1100°C and 1350°C, depending on the composition. The melting conditions were optimized in order to achieve a higher transparency. The optical, mechanical and thermal properties of the samples were measured and compared to the standard borosilicate and soda-lime glasses.

The growth of the industrial production generates a high volume of waste materials. These products have a significant impact on the environment. Therefore, the valorization of industrial wastes, especially those produced in huge quantities, is an important social and ecological issue. Waste reuse and recycling could help to develop new products and aggregate value to materials that would have been previously discarded. Furthermore, it could reduce the consumption of natural resources and pollution. Blast furnace slag and fly ash are waste materials largely used in concrete production, mainly as an aggregate, and road construction, as porous asphalt and in other contexts. These wastes contain many elements that are also present in typical glass formulas, such as CaO, SiO2, Al2O3, and Fe2O3. However, these elements are highly refractory, and their presence in complex compositions leads to a high tendency to crystallize and to...

The growth of the industrial production generates a high volume of waste materials. These products have a significant impact on the environment. Therefore, the valorization of industrial wastes, especially those produced in huge quantities, is an important social and ecological issue. Waste...

The paper is focussed on partition walls assembled from hollow glass blocks. These blocks gained popularity recently because of new development: new decors, wide range of colours, variable surface finishing and wide range of accessories make it attractive for architects. In addition, improvements in acoustic and thermal properties, improved fire resistance and further innovations lead to new applications. The traditional method of assembling is based on using of cement mortar and steel reinforcement leading in kind of reinforcement concrete structure. However, the growing popularity demands new, easier and faster installation methods as is the Vitralock system. It consists of two plastic elements and steel reinforcement. The elements are easily assembled, there is no need for special tools and skills. The performance of the system needs to be verified and reliable design model and application rules need to be prepared. Extensive test programme was carried out at Czech technical University in Prague. It include full-scale test of the wall loaded by horizontal load to evaluate the overall performance. The test is briefly described in the paper. In addition, component tests were performed to obtain properties of several parts of the system. These tests allow to build component finite element model which can be used to predict the response of the wall. Detailed description of these tests and basic information about the model is included here.

The paper is focussed on partition walls assembled from hollow glass blocks. These blocks gained popularity recently because of new development: new decors, wide range of colours, variable surface finishing and wide range of accessories make it attractive for architects. In addition, improvements in acoustic and thermal properties, improved fire resistance and further innovations lead to new applications. The traditional method of assembling is based on using of cement mortar and steel reinforcement leading in kind of reinforcement concrete structure. However, the growing popularity demands new, easier and faster installation methods as is the Vitralock system. It consists of two plastic elements and steel reinforcement. The elements are easily assembled, there is no need for special tools and skills. The performance of the system needs to be verified and reliable design model and application rules need to be prepared. Extensive test...

The paper is focussed on partition walls assembled from hollow glass blocks. These blocks gained popularity recently because of new development: new decors, wide range of colours, variable surface finishing and wide range of accessories make it attractive...

In the last decade there has been an increased usage of cast glass as structural element. Within this respect, a 14 m span glass masonry arch bridge is planned to be constructed at the TU Delft Campus. This paper focuses on part of the experimental analysis that was executed to develop the concept of this bridge. Since it is an arch, the applied loads will be transferred as compressive forces, hence the suitability of glass. Adhesive bonding is not required, since the arch isin compression under its own weight. Application of cast glass bricks in a bridge is a new concept, therefore several aspects with respect to the structural behavior are unknown. Two experimental tests are presented in this paper. First, an experiment with a stacked glass column with varying interlayers is loaded to investigate the stiffness of the interlayer. For PVC interlayers the time-dependent behavior is significant, whereas for polyurethane it is minimal. Furthermore the interlayer’s equivalent modulus of elasticity is dependent on the thickness, due to a difference in the occurring contact areas. Second, a small-scale glass masonry arch is loaded till collapse to investigate the failure behavior and the stresses distribution. It was concluded that a certain robustness is present in the system. Furthermore the brick geometry and the occurrence of sliding are the main aspects that determine the stress distribution. Therewith a stiffer interlayer results in higher stresses in the glass.

In the last decade there has been an increased usage of cast glass as structural element. Within this respect, a 14 m span glass masonry arch bridge is planned to be constructed at the TU Delft Campus. This paper focuses on part of the experimental analysis that was executed to develop the concept of this bridge. Since it is an arch, the applied loads will be transferred as compressive forces, hence the suitability of glass. Adhesive bonding is not required, since the arch isin compression under its own weight. Application of cast glass bricks in a bridge is a new concept, therefore several aspects with respect to the structural behavior are unknown. Two experimental tests are presented in this paper. First, an experiment with a stacked glass column with varying interlayers is loaded to investigate the stiffness of the interlayer. For PVC interlayers the time-dependent behavior is significant, whereas for polyurethane it is minimal. Furthermore the interlayer’s equivalent...

In the last decade there has been an increased usage of cast glass as structural element. Within this respect, a 14 m span glass masonry arch bridge is planned to be constructed at the TU Delft Campus. This paper focuses on part of the experimental analysis that was executed to develop the...

This study aims to investigate and assess the analytical calculation methods which are applicable to glass parapets. Specifically it is focused on glass parapets, which are continuously clamped along their lower edge in an aluminium profile, without the addition of a (structural) handrail. The starting point of the research are the current codes of practice regarding glass parapets. The objectives are to investigate the limitations of the current methods, to develop new methods and to test whether these are applicable, taking into account the standards of several European countries. Codes and standards from the Netherlands, Belgium, the United Kingdom and Germany are analysed and applied to the calculation methods, to identify and analyse the differences. Subsequently, a series of static load tests have been performed to determine the spring stiffness of the aluminium parapet clamping profiles, such that they can be applied in new analytical calculation methods. The long-term value of this research is to present more accurate calculation methods which can be applied to continuously supported glass parapet, accounting for different parameters, such as the supporting effect of sealing rubbers and the application depth of fixation wedges. Finally, recommendations are made to improve common calculation methods.

This study aims to investigate and assess the analytical calculation methods which are applicable to glass parapets. Specifically it is focused on glass parapets, which are continuously clamped along their lower edge in an aluminium profile, without the addition of a (structural) handrail. The starting point of the research are the current codes of practice regarding glass parapets. The objectives are to investigate the limitations of the current methods, to develop new methods and to test whether these are applicable, taking into account the standards of several European countries. Codes and standards from the Netherlands, Belgium, the United Kingdom and Germany are analysed and applied to the calculation methods, to identify and analyse the differences. Subsequently, a series of static load tests have been performed to determine the spring stiffness of the aluminium parapet clamping profiles, such that they can be applied in new analytical calculation methods. The long-term...

This study aims to investigate and assess the analytical calculation methods which are applicable to glass parapets. Specifically it is focused on glass parapets, which are continuously clamped along their lower edge in an aluminium profile, without the addition of a (structural) handrail. The...

Projects & Case studies

Modern cities and their architectural structures undergo significant functional and physical changes. In recent years, the interventions on building envelopes have increased. Therefore, it is necessary to analyze potential remodeling of glass facades, along with applying the concept of smart technologies, in order to increase energy efficiency of the existing buildings. This paper analyzes the modernization process of devastated glass façade of the tall Slavija hotel, built in 1960s in Belgrade, Serbia, taking into consideration some positive examples of transformation and reskinning of buildings, where the aspect of medialization is an active part of urban renewal. The subject of this paper is the analysis of research findings about the improved thermal comfort of this building, after performing the replacement of its glass façade and converting the hotel building into a office building. Special attention was paid to the implementation of media facades technologies and final effects on energy balance of the newly designed facade. The proposed solution is supposed to evaluate the improved thermal comfort that was achieved by a radical renovation of the facade and by replacing the existing facade with a new single façade (double and triple glazed units), with media elements as well as without them. The research results are presented as proposals for improving EE public buildings by implementing the latest system of curtain walls in order to increase the value of the buildings. One of the most important criteria included in the process of energy refurbishment is technological improvement of the existing buildings, along with the presentation of media facades. The case study is based on Energy Plus simulations.

Modern cities and their architectural structures undergo significant functional and physical changes. In recent years, the interventions on building envelopes have increased. Therefore, it is necessary to analyze potential remodeling of glass facades, along with applying the concept of smart technologies, in order to increase energy efficiency of the existing buildings. This paper analyzes the modernization process of devastated glass façade of the tall Slavija hotel, built in 1960s in Belgrade, Serbia, taking into consideration some positive examples of transformation and reskinning of buildings, where the aspect of medialization is an active part of urban renewal. The subject of this paper is the analysis of research findings about the improved thermal comfort of this building, after performing the replacement of its glass façade and converting the hotel building into a office building. Special attention was paid to the implementation of...

Modern cities and their architectural structures undergo significant functional and physical changes. In recent years, the interventions on building envelopes have increased. Therefore, it is necessary to analyze potential remodeling of glass facades,...

The aim of this paper is to explain how the design intent of a bespoke glazed façade develops from the point of view of the façade consultant BIFF SA. The explanation of this concept development is not only interesting because of the different phases of the process, but also because of the unusual specifications and demands established by the architects and the Client, and for the project evolution trough several technical solutions up to final project state. During the concept development materials like stone, steel, aluminum or fabric are normally combined with glass. This challenging glazed façade has been developed for a luxury villa in Switzerland where a triple laminated glass cladding has been selected as the final most suitable solution for creating a building envelope with glass panes of 3000mm W x 7000mm H bonded to a back frame with structural silicone. These units have obviously aesthetic requirements and also different functional applications and the solution should fulfill all demands and do not the technical aspects of building up a façade with such a big glass units.

The aim of this paper is to explain how the design intent of a bespoke glazed façade develops from the point of view of the façade consultant BIFF SA. The explanation of this concept development is not only interesting because of the different phases of the process, but also because of the unusual specifications and demands established by the architects and the Client, and for the project evolution trough several technical solutions up to final project state. During the concept development materials like stone, steel, aluminum or fabric are normally combined with glass. This challenging glazed façade has been developed for a luxury villa in Switzerland where a triple laminated glass cladding has been selected as the final most suitable solution for creating a building envelope with glass panes of 3000mm W x 7000mm H bonded to a back frame with structural silicone. These units have obviously aesthetic requirements and also different functional applications and the solution...

The aim of this paper is to explain how the design intent of a bespoke glazed façade develops from the point of view of the façade consultant BIFF SA. The explanation of this concept development is not only interesting because of the different phases of the process, but also because of the...

Future smart cities are demanding for new infrastructures and networks. Novel multifunctional objects should be able to acquire, store and transmit information, generate their own energy need, light up the surroundings and more. Thanks to their transparency, glass structures are ideal support for hi-tech components because of the inherent opportunity offered by laminated glass to embed PV cells, sensors, OLEDs and lighting devices. The project HYbrid GLAss-Steel Stele (HYGLASS) aims at the realization of a cantilevering hybrid vertical structure working as a stand-alone or a grid-connected smart tower. The facetted geometry of the construction originates from the tetrahelix solid, and its structural conception is based on segmentation and post-tensioning, which are the same basic principles of the Travi Vitree Tensegrity (TVT). The spatial complexity and the height of the tower (about 7.00 meters) requires a high ULS safety level that is obtained by designing the structure to withstand the worst-case scenario of all panels cracked. To this purpose and to facilitate the assembly operations, a filigree metal skeleton is placed at the edges of the base polyhedron. Equal triangular glass panels are corner clamped into special nodes at the vertices of the solid. Modularity and dry connections facilitate an easy replacement of the damaged components. FE nonlinear analyses highlight the safe design and efficiency of the system. Such structural concept is the key to extent the hybrid glass-steel construction to the domain of self-supporting high-rise and long-spanned structures or building skins.

Future smart cities are demanding for new infrastructures and networks. Novel multifunctional objects should be able to acquire, store and transmit information, generate their own energy need, light up the surroundings and more. Thanks to their transparency, glass structures are ideal support for hi-tech components because of the inherent opportunity offered by laminated glass to embed PV cells, sensors, OLEDs and lighting devices. The project HYbrid GLAss-Steel Stele (HYGLASS) aims at the realization of a cantilevering hybrid vertical structure working as a stand-alone or a grid-connected smart tower. The facetted geometry of the construction originates from the tetrahelix solid, and its structural conception is based on segmentation and post-tensioning, which are the same basic principles of the Travi Vitree Tensegrity (TVT). The spatial complexity and the height of the tower (about 7.00 meters) requires a high ULS safety level that is obtained by designing the structure...

Future smart cities are demanding for new infrastructures and networks. Novel multifunctional objects should be able to acquire, store and transmit information, generate their own energy need, light up the surroundings and more. Thanks to their transparency, glass structures are ideal...

Laminated safety glass with structural PVB interlayer is suitable for a variety of challenging applications in building construction and façade design. Especially in areas with increased static requirements, stiffer interlayer materials are preferred to standard PVB films. This results in a reduction in the number of glass panes or pane thicknesses while maintaining comparable properties. The attainment of relevant safety properties in combination with advantages in both processing and economic terms often allows a more reasonable application than the use of appropriate laminated glass with ionomer interlayers. A new filter factory of a well-known medical technology company is currently being built in Wilsdruff on the outskirts of Dresden. The company's own competence campus is glazed with large-format glass elements. The new building of the Wilsdruff filter factory represents the first application of large-format laminated safety glass panes with structural PVB interlayer under the approach of the shear coupling in Germany. Both the pane sizes of 7.25 m x 2.40 m and the type of two-sided linear support of the façade panes are extraordinary and unique in Germany in this combination. Based on the material properties of the PVB film, the advantages of such elements are demonstrated. It can be seen that projects such as the Wilsdruff filter factory can only be realized in this form by using stiffer interlayers. This project thus demonstrates the possibilities of using such laminated safety glass and thus helps to increase the acceptance of architects, planners and building owners.

Laminated safety glass with structural PVB interlayer is suitable for a variety of challenging applications in building construction and façade design. Especially in areas with increased static requirements, stiffer interlayer materials are preferred to standard PVB films. This results in a reduction in the number of glass panes or pane thicknesses while maintaining comparable properties. The attainment of relevant safety properties in combination with advantages in both processing and economic terms often allows a more reasonable application than the use of appropriate laminated glass with ionomer interlayers. A new filter factory of a well-known medical technology company is currently being built in Wilsdruff on the outskirts of Dresden. The company's own competence campus is glazed with large-format glass elements. The new building of the Wilsdruff filter factory represents the first application of large-format laminated safety glass...

Laminated safety glass with structural PVB interlayer is suitable for a variety of challenging applications in building construction and façade design. Especially in areas with increased static requirements, stiffer interlayer materials are preferred to...

The paper illustrates the design project of the main laminated glass balustrade of a steel staircase installed in the historical Margherita Theatre in Livorno, Italy. After its final closure, almost 15 years ago, the new owners decided to refurbish the building and to convert it into a shopping center. The entire project was developed with particular attention to the conservation of the building style. In order to join the ground level to the former gallery level a new steel staircase has been placed and three laminated glass balustrades were added. The bigger one is a big rectangular glazing 4047 long and 5765 mm high consisting of 8 rectangular laminated glass panels, each composed of two 12 thick fully tempered glass sheets laminated with PVB interlayer. Unique steel connections were designed and built in order to join the glass panels to each other and to the steel staircase. The connections to the staircase were designed so to avoid the out-of-plane movements of the glass panels, and to allow the free vertical relative movement between staircase and glass. The horizontal out-of-plane movements of the top edge of the big glazing is prevented owing to a horizontal 5600 mm long laminated glass fin. The paper illustrates the design and check of the glass panels, their geometry and functioning, the numerical analyses and the results.

The paper illustrates the design project of the main laminated glass balustrade of a steel staircase installed in the historical Margherita Theatre in Livorno, Italy. After its final closure, almost 15 years ago, the new owners decided to refurbish the building and to convert it into a shopping center. The entire project was developed with particular attention to the conservation of the building style. In order to join the ground level to the former gallery level a new steel staircase has been placed and three laminated glass balustrades were added. The bigger one is a big rectangular glazing 4047 long and 5765 mm high consisting of 8 rectangular laminated glass panels, each composed of two 12 thick fully tempered glass sheets laminated with PVB interlayer. Unique steel connections were designed and built in order to join the glass panels to each other and to the steel staircase. The connections to the staircase were designed so to avoid the out-of-plane movements of the glass...

The paper illustrates the design project of the main laminated glass balustrade of a steel staircase installed in the historical Margherita Theatre in Livorno, Italy. After its final closure, almost 15 years ago, the new owners decided to refurbish the building and to convert it into a...

The plan of the glass group of the TU Delft to realize a 14m span dry-stacked glass arched masonry bridge led to investigation of stability of glass arches in more general. Analytical and numerical analysis are done to compare results. Analytical analyses are based on methods developed for traditional stone arches. A graph is plotted in which the relationship between rise-to-span ratio and thickness-to-span ratio is derived and presented such that the relevant instability mechanism(s) can be determined. The required thickness of a stable arch can be found by applying a geometrical factor of safety. To investigate 2nd order effects and stresses, finite element models are presented. The models verify the analytical solutions and are used to investigate the influence of axial stiffness and nonlinear effects on stability.

The plan of the glass group of the TU Delft to realize a 14m span dry-stacked glass arched masonry bridge led to investigation of stability of glass arches in more general. Analytical and numerical analysis are done to compare results. Analytical analyses are based on methods developed for traditional stone arches. A graph is plotted in which the relationship between rise-to-span ratio and thickness-to-span ratio is derived and presented such that the relevant instability mechanism(s) can be determined. The required thickness of a stable arch can be found by applying a geometrical factor of safety. To investigate 2nd order effects and stresses, finite element models are presented. The models verify the analytical solutions and are used to investigate the influence of axial stiffness and nonlinear effects on stability.

The plan of the glass group of the TU Delft to realize a 14m span dry-stacked glass arched masonry bridge led to investigation of stability of glass arches in more general. Analytical and numerical analysis are done to compare results. Analytical analyses...

On the campus of Delft University the Glass and Transparency Research Group is preparing to build a pedestrian bridge as a low arch consisting of dry-stacked glass blocks. As temporary support for the arch, a lens-shaped truss has been constructed and placed on location. This truss has been fitted with as many glass components as was structurally feasible. The diagonals in the truss are glass bundle struts and the nodes of the truss are cast glass components. The lenticular truss will serve as a temporary bridge during the time the team needs to prepare for construction of the eventual Glass Arch Bridge. Due to the experimental nature of the truss, with its unusual and novel applications of structural glass, a number of demonstrative proof loadings were performed to ease concerns about the safety of the structure. The glass bundles have been proof-loaded to twice their maximum expected load just prior to their installation in the structure. The whole system has then been proof-loaded for several critical load combinations (static and dynamic) just after installation. During the proof-loading the strains in the glass diagonals have been measured. These lie easily within the acceptable limits. In the paper the structural design of the bridge, in particular the glass node connector and the glass bundle diagonals will be explained. Then the proof-loading of the bridge will be described. Then the results of the proof-loading are presented and discussed.

On the campus of Delft University the Glass and Transparency Research Group is preparing to build a pedestrian bridge as a low arch consisting of dry-stacked glass blocks. As temporary support for the arch, a lens-shaped truss has been constructed and placed on location. This truss has been fitted with as many glass components as was structurally feasible. The diagonals in the truss are glass bundle struts and the nodes of the truss are cast glass components. The lenticular truss will serve as a temporary bridge during the time the team needs to prepare for construction of the eventual Glass Arch Bridge. Due to the experimental nature of the truss, with its unusual and novel applications of structural glass, a number of demonstrative proof loadings were performed to ease concerns about the safety of the structure. The glass bundles have been proof-loaded to twice their maximum expected load just prior to their installation in the structure. The whole system has then been...

On the campus of Delft University the Glass and Transparency Research Group is preparing to build a pedestrian bridge as a low arch consisting of dry-stacked glass blocks. As temporary support for the arch, a lens-shaped truss has been constructed and placed on location. This truss has been...

An all-glass balustrade’s continuous handrail enables a horizontal load transfer from more flexible glass panes into adjacent elements with higher stiffness and thereafter – as the case may be – into even more rigid parts of the structure. As all the glass units are interconnected thus supporting each other mutually, a safe and economic design either requires taking a holistic view of the entire structural system or to make appropriate assumptions for the boundary conditions of the handrail in order to assess precisely the stress state of a single element of an all-glass railing. The idea of the method presented is to set elastic springs at the ends of the single element’s rail to simulate the stiffness of the adjacent glazing. As these elements are usually charged by wind or horizontal live load, too, the additional supports must not be applied for the entire load and are therefore divided in up to three parts. Each part is put onto a corresponding model of the considered single element and glass stresses are calculated subsequently. Finally, the superposition principle leads to the actual maximum stress. Within a parameter study the new method is compared to former methods and to the results of calculations done with extended FEA-models that comprise the neighbouring structure. The new approach shows a good accordance with the latter and exceeds the former methods by far. Hence it contributes to a more economic glass design.

An all-glass balustrade’s continuous handrail enables a horizontal load transfer from more flexible glass panes into adjacent elements with higher stiffness and thereafter – as the case may be – into even more rigid parts of the structure. As all the glass units are interconnected thus supporting each other mutually, a safe and economic design either requires taking a holistic view of the entire structural system or to make appropriate assumptions for the boundary conditions of the handrail in order to assess precisely the stress state of a single element of an all-glass railing. The idea of the method presented is to set elastic springs at the ends of the single element’s rail to simulate the stiffness of the adjacent glazing. As these elements are usually charged by wind or horizontal live load, too, the additional supports must not be applied for the entire load and are therefore divided in up to three parts. Each part is put onto...

An all-glass balustrade’s continuous handrail enables a horizontal load transfer from more flexible glass panes into adjacent elements with higher stiffness and thereafter – as the case may be – into even more rigid parts of the structure. As all...

This paper will describe the design, detailing, testing and construction of the structural glass beams which make up the load bearing grid shell structure of the newly built Zaryadye Park in Moscow, Russia. The canopy structure is situated short distance from Red Square and the Kremlin. Structural glass beams, 72 in total, are connected into the main undulating steel grid shell structure which measures approximately 120m long and 60m wide. The beams themselves vary in length according to the geometry but are generally 3m long, 0.2m deep. The beams meet each other and the main steel structure at bespoke stainless steel nodes, and are topped by triangular glass roof panels. The glass beams were designed to accommodate Moscow’s extreme weather conditions, with drifted snow loads of up to 350 kg/m2. Differential movement of the main structure was another challenge for the design team, and required sophisticated linear analysis with over 150 load combinations. The resulting movements called for further development of the nodal connections and non-linear analysis of their performance. Due to a lack of legislation covering structural glass in Russia a so called ‘Special Technical Standard’ was required. This document was written with significant input from us and covers the technical aspects of glass and its performance. A full scale mock-up of one roof panel, complete with beams and node connections, was constructed and tested to gain approvals from the authorities. Zaryadye Park is Moscow’s first new major landmark in 50 years and was opened on the 9th of September in time for the City Day celebrations.

This paper will describe the design, detailing, testing and construction of the structural glass beams which make up the load bearing grid shell structure of the newly built Zaryadye Park in Moscow, Russia. The canopy structure is situated short distance from Red Square and the Kremlin. Structural glass beams, 72 in total, are connected into the main undulating steel grid shell structure which measures approximately 120m long and 60m wide. The beams themselves vary in length according to the geometry but are generally 3m long, 0.2m deep. The beams meet each other and the main steel structure at bespoke stainless steel nodes, and are topped by triangular glass roof panels. The glass beams were designed to accommodate Moscow’s extreme weather conditions, with drifted snow loads of up to 350 kg/m2. Differential movement of the main structure was another challenge for the design team, and required sophisticated linear analysis with over 150 load combinations. The...

This paper will describe the design, detailing, testing and construction of the structural glass beams which make up the load bearing grid shell structure of the newly built Zaryadye Park in Moscow, Russia. The canopy structure is situated short distance from Red Square and the Kremlin....

The state owned building of the Land Registry in Ravensburg, South Germany, got a new glass façade in front of the staircase. The artistic design, which is inspired by a crumpled piece of paper, is realized by laser treatment and digital printing with ceramic enamels. It is integrated in nine panels of insulating glass.

The state owned building of the Land Registry in Ravensburg, South Germany, got a new glass façade in front of the staircase. The artistic design, which is inspired by a crumpled piece of paper, is realized by laser treatment and digital printing with ceramic enamels. It is integrated in nine panels of insulating glass.

The state owned building of the Land Registry in Ravensburg, South Germany, got a new glass façade in front of the staircase. The artistic design, which is inspired by a crumpled piece of paper, is realized by laser treatment and digital printing with...

Revolving entrance doors - usually built as some kind of all glass structure - are part of many publicly accessible buildings. As the architectural demands rise regarding transparency and slenderness of façade members, the entrance doors have to and do go along with these demands. But even if the façade is designed carefully and verified according all relevant standards, the revolving doors are usually considered as a machine, coming with some certificate. This point of view is mostly shared by the manufacturer and the basis for the call for proposals. The certificates provided by the door manufacturer considers the electrical safety, the safety aspects for people handling and using the doors regarding the risk of persons being jammed or hit by the turning door leaves, but not the structural safety of the door system in means of resistance to live, dead, wind or earthquake loads. If we look at the design and verification effort made for standard façade elements, even windows on the one hand, and the different failure consequences for windows and revolving doors on the other hand, it becomes obvious that especially to non-standard and large-scale doors should be paid some attention regarding its structural safety. Below the legal situation of revolving doors is considered in the European context and two quite different examples of revolving doors are discussed regarding their structural assessment.

Revolving entrance doors - usually built as some kind of all glass structure - are part of many publicly accessible buildings. As the architectural demands rise regarding transparency and slenderness of façade members, the entrance doors have to and do go along with these demands. But even if the façade is designed carefully and verified according all relevant standards, the revolving doors are usually considered as a machine, coming with some certificate. This point of view is mostly shared by the manufacturer and the basis for the call for proposals. The certificates provided by the door manufacturer considers the electrical safety, the safety aspects for people handling and using the doors regarding the risk of persons being jammed or hit by the turning door leaves, but not the structural safety of the door system in means of resistance to live, dead, wind or earthquake loads. If we look at the design and verification effort made for standard façade elements, even windows...

Revolving entrance doors - usually built as some kind of all glass structure - are part of many publicly accessible buildings. As the architectural demands rise regarding transparency and slenderness of façade members, the entrance doors have to and do go along with these demands. But even if...

The iconic Torre Europa building in Madrid is currently under refurbishment. The envisaged works include the construction of a new entrance hall composed of two structural glass façades and a steel canopy above them. This paper focuses on the design and construction of the two structural glass façades, which are connected together at an angle of 100∘. These are made up of a number of laminated glass panels standing on the ground floor slab and stabilised by vertical glass fins. The connection between the cladding panels and the fins is resolved with embedded metal connectors. The top end of the fins is connected to an horizontal glass beam that extends along the two façades, thus forming an Lshape with both ends fixed to the primary structure of the building. This beam is a critical structural element that carries 50% of the wind load applied to the façades and may be also exposed to some vertical load such as snow.

The iconic Torre Europa building in Madrid is currently under refurbishment. The envisaged works include the construction of a new entrance hall composed of two structural glass façades and a steel canopy above them. This paper focuses on the design and construction of the two structural glass façades, which are connected together at an angle of 100∘. These are made up of a number of laminated glass panels standing on the ground floor slab and stabilised by vertical glass fins. The connection between the cladding panels and the fins is resolved with embedded metal connectors. The top end of the fins is connected to an horizontal glass beam that extends along the two façades, thus forming an Lshape with both ends fixed to the primary structure of the building. This beam is a critical structural element that carries 50% of the wind load applied to the façades and may be also exposed to some vertical load such as snow.

The iconic Torre Europa building in Madrid is currently under refurbishment. The envisaged works include the construction of a new entrance hall composed of two structural glass façades and a steel canopy above them. This paper focuses on the design and construction of the two structural...

La Maison des Fondateurs in Le Brassus Switzerland is going to represent the watch making manufacture Audemars Piguet. Audemars Piguet stands for the finest quality, precision as well as innovation based on traditional watchmaking expertise and craftsmanship. La Maison des Fondateurs has been developed from a competition proposal to the execution project by the architects BIG – Bjarke Ingels Group. The created interlocking all glass spiral evolves the building volume out of the rough, natural landscape providing a perfect linear museum path for the building program. Despite the severe loading and weather conditions, inspired by the high values of Audemars Piguet the project team designed the building to the technical limits. The curved and very large insulated façade glass units as well as the curved glass partition walls of the interlocking glass spiral are forming the load bearing structure. All vertical and horizontal loads are transferred by these glass components making solid columns and shear wall obsolete. The article reflects the close collaboration of the designers, engineers, specialist contractor and industry. The global structural concept, transfer of the concentrated point loading into the curved structural glass element, testing procedures as well as the structural bonding beyond standards and the context of energy efficiency are discussed and elaborated.

La Maison des Fondateurs in Le Brassus Switzerland is going to represent the watch making manufacture Audemars Piguet. Audemars Piguet stands for the finest quality, precision as well as innovation based on traditional watchmaking expertise and craftsmanship. La Maison des Fondateurs has been developed from a competition proposal to the execution project by the architects BIG – Bjarke Ingels Group. The created interlocking all glass spiral evolves the building volume out of the rough, natural landscape providing a perfect linear museum path for the building program. Despite the severe loading and weather conditions, inspired by the high values of Audemars Piguet the project team designed the building to the technical limits. The curved and very large insulated façade glass units as well as the curved glass partition walls of the interlocking glass spiral are forming the load bearing structure. All vertical and horizontal loads are transferred by these glass components making...

La Maison des Fondateurs in Le Brassus Switzerland is going to represent the watch making manufacture Audemars Piguet. Audemars Piguet stands for the finest quality, precision as well as innovation based on traditional watchmaking expertise and craftsmanship. La Maison des Fondateurs has been...

Sarah Oppenheimer is an artist whose work with glass challenges our perception of space. David Bott (PE, SE, AIA) of Heintges Consulting Architects & Engineers assisted Oppenheimer in developing structural solutions that do not always conform to traditional architectural parameters, often when there are no precedents in building codes. Bott highlights the apparent lack of clear glass engineering guidance in both the International Building Code and the ASTM E1300 standard. He goes on to explore the importance of utilizing information hidden deep within E1300 or contained in other codes and glass engineering literature, to tackle unique structural design situations. Engineering experience and imagination are not only relevant, but required. Two Oppenheimer projects are presented illustrating how the engineer overcame unusual structural challenges to help the artist develop her installations. The first project, a permanent entryway sculpture entitled P-131317, primarily consists of two oversized lites of glass sloped at 45 degrees, between which occupants enter and leave an academic building. The second project, a temporary gallery installation entitled 33-D, comprises two trapezoidal sheets of glass mounted through openings in the gallery’s partition walls. The bottom edge of each angular glass lite floats just above the floor plane with only three minimal support points.

Sarah Oppenheimer is an artist whose work with glass challenges our perception of space. David Bott (PE, SE, AIA) of Heintges Consulting Architects & Engineers assisted Oppenheimer in developing structural solutions that do not always conform to traditional architectural parameters, often when there are no precedents in building codes. Bott highlights the apparent lack of clear glass engineering guidance in both the International Building Code and the ASTM E1300 standard. He goes on to explore the importance of utilizing information hidden deep within E1300 or contained in other codes and glass engineering literature, to tackle unique structural design situations. Engineering experience and imagination are not only relevant, but required. Two Oppenheimer projects are presented illustrating how the engineer overcame unusual structural challenges to help the artist develop her installations. The first project, a permanent entryway sculpture entitled P-131317, primarily consists...

Stability & Strength

Glass, a brittle material, fractures under tensile stress acting over a time duration. Lateral loads, such as wind, acting on a simply supported rectangular glass lite, put one surface of the lite primarily into tension. ASTM E 1300 defines load resistance of glass as the uniform lateral loading acting over a duration of 3 seconds that is associated with a probability of breakage of 8 lites per 1000 at the first occurrence of the loading. To determine load resistance, the underlying window glass failure prediction model facilitates determination of a probability distribution of 3 second equivalent failure loads, P3. The glass failure prediction model is based on a Weibull distribution, and most people believe the distribution of P3 is, in fact, a Weibull distribution. However, the authors contend that this is not the case. This paper provides an explanation of the glass failure prediction model, its basis, and a discussion of the method for determining surface flaw parameters with an example. The authors demonstrate the distribution of the equivalent failure loads does not follow a Weibull distribution, and they will elucidate the relationship between the distribution of P3 and the Weibull distribution.

Glass, a brittle material, fractures under tensile stress acting over a time duration. Lateral loads, such as wind, acting on a simply supported rectangular glass lite, put one surface of the lite primarily into tension. ASTM E 1300 defines load resistance of glass as the uniform lateral loading acting over a duration of 3 seconds that is associated with a probability of breakage of 8 lites per 1000 at the first occurrence of the loading. To determine load resistance, the underlying window glass failure prediction model facilitates determination of a probability distribution of 3 second equivalent failure loads, P3. The glass failure prediction model is based on a Weibull distribution, and most people believe the distribution of P3 is, in fact, a Weibull distribution. However, the authors contend that this is not the case. This paper provides an explanation of the glass failure prediction model, its basis, and a discussion of the method for determining...

Glass, a brittle material, fractures under tensile stress acting over a time duration. Lateral loads, such as wind, acting on a simply supported rectangular glass lite, put one surface of the lite primarily into tension. ASTM E 1300 defines load resistance of glass as the uniform lateral...

Cold bent glass is nowadays of primary importance both for industrial and civil applications. In fact, thin glass with a maximum thickness of 1.5 mm is often part of a wide range of technological devices and architectural surfaces (e.g. touchscreens, displays, mirrors, optical instruments, claddings and building interiors). The manufacturing process of cold bent glass is generally considered faster and less demanding in terms of necessary equipment with respect to hot bending or casting techniques. On the contrary, both the design of the manufacturing procedure and of the products are still a challenge and they are mainly based on a trial and error approach. Generalized defects and imperfections are always present on the surface of the raw glass product, while another significant source of flaws is usually localized at the edges and it is associated with the specific cutting technique and edges processing. The aim of this work is to experimental investigate the influence of the edge processing on the failure strength of 1.5 mm glass plates by means of four point bending tests. Two edge conditions are taken into account: manual diamond cut and ground by hand-operated tool which introduces randomly diffused small-size flaws. Test results are then statistically assessed and compared with the stresses that arise during the cold bending process due to the imposed curvature. In the end, grinding somehow increases the level of damage as it increases the number of flaws. On the contrary, the improved uniformity of the damage leads to less scattered resistance values. These allows to achieve smaller curvature radii or, for a given design radius, it reduces accidental failures during the cold bending process.

Cold bent glass is nowadays of primary importance both for industrial and civil applications. In fact, thin glass with a maximum thickness of 1.5 mm is often part of a wide range of technological devices and architectural surfaces (e.g. touchscreens, displays, mirrors, optical instruments, claddings and building interiors). The manufacturing process of cold bent glass is generally considered faster and less demanding in terms of necessary equipment with respect to hot bending or casting techniques. On the contrary, both the design of the manufacturing procedure and of the products are still a challenge and they are mainly based on a trial and error approach. Generalized defects and imperfections are always present on the surface of the raw glass product, while another significant source of flaws is usually localized at the edges and it is associated with the specific cutting technique and edges processing. The aim of this work is to experimental investigate the influence of the...

Cold bent glass is nowadays of primary importance both for industrial and civil applications. In fact, thin glass with a maximum thickness of 1.5 mm is often part of a wide range of technological devices and architectural surfaces (e.g. touchscreens, displays, mirrors, optical instruments,...

A numerical method is applied to model the fracture stress and failure location in glass panes subjected to various bending arrangements. The method assumes the weakest-link principle and the existence of surface microcracks. The fracture stress and failure origin are revealed through a search algorithm. The magnitude of strength and the location of fracture are stochastic in nature and can be predicted based on a suitable representation of the surface flaws condition. When the crack size distribution is assumed to be Pareto, the strength distribution is found to be very similar to a Weibull distribution. The stresses in large laterally supported plates which are subjected to uniform pressure are modelled and the distribution of fracture location is determined based on a single population of cracks with a Pareto distributed crack size. Two types of gasket support materials are considered, neoprene and nylon. The softer gasket material produces a greater number of fractures nearer the corners of the plate. A comparison is made with the recorded fracture locations according to various experiments. In addition, a tall vertical panel of laminated glass with a complex geometry and which is subjected to dynamic impact loading is modelled and the distribution of fracture location is determined based on a single population of cracks with a Pareto distributed crack size.

A numerical method is applied to model the fracture stress and failure location in glass panes subjected to various bending arrangements. The method assumes the weakest-link principle and the existence of surface microcracks. The fracture stress and failure origin are revealed through a search algorithm. The magnitude of strength and the location of fracture are stochastic in nature and can be predicted based on a suitable representation of the surface flaws condition. When the crack size distribution is assumed to be Pareto, the strength distribution is found to be very similar to a Weibull distribution. The stresses in large laterally supported plates which are subjected to uniform pressure are modelled and the distribution of fracture location is determined based on a single population of cracks with a Pareto distributed crack size. Two types of gasket support materials are considered, neoprene and nylon. The softer gasket material produces a greater number of fractures nearer...

A numerical method is applied to model the fracture stress and failure location in glass panes subjected to various bending arrangements. The method assumes the weakest-link principle and the existence of surface microcracks. The fracture stress and failure origin are revealed through a search...

The paper correlates the data recorded in Stazione Sperimentale del Vetro, in many years. The aim is to define a correlation between the following parameters in heat treated glass: 1) bending strength tested according EN 1288-3 ; 2) fragmentation tested according relevant Standards [EN 1863-1 2004, EN12150-1 2015, EN 14179-1 2016]; 3) surface compression stress measured with laser Gasp [ASTM C1279 2013]. For heat strengthened glass the fragmentation correlation due to the different crack path ("island" fragments instead of small fragments) is only related to conformity: Y/N. The research is the development of the previous ones [Schiavonato et al. 2005, Mognato et al. 2011] carried out at Stazione Sperimentale Vetro, increasing the experimental data (up to 2017)considering in detail the emissivity of coated glass and extending also to enamelled glass. The correlation between surface compression stress and mechanical strength and fragmentation is relevant for the manufacturer, who may use surface pre-stress measurement as a means of product control.

The paper correlates the data recorded in Stazione Sperimentale del Vetro, in many years. The aim is to define a correlation between the following parameters in heat treated glass: 1) bending strength tested according EN 1288-3 ; 2) fragmentation tested according relevant Standards [EN 1863-1 2004, EN12150-1 2015, EN 14179-1 2016]; 3) surface compression stress measured with laser Gasp [ASTM C1279 2013]. For heat strengthened glass the fragmentation correlation due to the different crack path ("island" fragments instead of small fragments) is only related to conformity: Y/N. The research is the development of the previous ones [Schiavonato et al. 2005, Mognato et al. 2011] carried out at Stazione Sperimentale Vetro, increasing the experimental data (up to 2017)considering in detail the emissivity of coated glass and extending also to enamelled glass. The correlation between surface compression stress and mechanical strength and fragmentation is relevant for the manufacturer, who...

The paper correlates the data recorded in Stazione Sperimentale del Vetro, in many years. The aim is to define a correlation between the following parameters in heat treated glass: 1) bending strength tested according EN 1288-3 ; 2) fragmentation tested according relevant Standards [EN 1863-1...

Thin glass is currently widespread in mobile devices and has great potential for applications in buildings. However, presently there is no standard method to determine the strength of thin glass for building applications and there is little experimental data available on its mechanical behaviour. Hence, this paper presents experimental and numerical investigations developed with two main goals: (i) to assess and (eventually) adapt existing test setups in order to determine the strength of thin glass; and (ii) to characterize thin glass using those tests, focusing on the ultimate strength of the material. The experimental programme, which was executed at TU Delft, comprised destructive tests on chemically tempered thin glass (thickness of 2 mm). Two destructive tests were assessed and tentatively improved: the in-plane four-point bending test, which involved many difficulties related with geometrical and mechanical instabilities; and the buckling test, which provided a lower bound for the material strength, as failure was triggered in the supports (due to stress concentrations). Based on the results obtained, a new tension test was proposed and numerically investigated; the results obtained revealed many advantages over the former tests in terms of quality/consistency of results and possibility of standardization.

Thin glass is currently widespread in mobile devices and has great potential for applications in buildings. However, presently there is no standard method to determine the strength of thin glass for building applications and there is little experimental data available on its mechanical behaviour. Hence, this paper presents experimental and numerical investigations developed with two main goals: (i) to assess and (eventually) adapt existing test setups in order to determine the strength of thin glass; and (ii) to characterize thin glass using those tests, focusing on the ultimate strength of the material. The experimental programme, which was executed at TU Delft, comprised destructive tests on chemically tempered thin glass (thickness of 2 mm). Two destructive tests were assessed and tentatively improved: the in-plane four-point bending test, which involved many difficulties related with geometrical and mechanical instabilities; and the buckling test, which provided a lower bound...

Thin glass is currently widespread in mobile devices and has great potential for applications in buildings. However, presently there is no standard method to determine the strength of thin glass for building applications and there is little experimental data available on its mechanical...

The use of glass in windows and curtain walls, in residential as well as in high-rise buildings, is something that requires great care in design and execution. Apart from complying with typical structural engineering practices and ensuring, for example, that the glass thickness is sufficient to withstand wind loads, impact loads etc. it is necessary always also to consider the thermal-stress resistance of the glass employed as well as the temperature distribution across glass and façade components. This topic is not new as it began to be analysed with the emergence of the first body tinted basic glass types. All the analysis done today is based on a linear approach and a more or less simplified algorithm. But modern constructions make it necessary to recognize special details and to acquire a more detailed view of the construction and use of such windows and curtain walls. Glass manufacturers can assist in this by helping to analyse the thermal stress characteristics but also the temperature distribution in different constructions. It is necessary here also to evaluate the different boundary conditions, which vary from location to location. The paper will begin by describing the basic methods for analysing the thermal-stress resistance of glazing units. But it will then go on to show the influence of the boundary conditions on the final result. The paper will also show the effect of a detailed 2D FE analysis in specifically analysing critical locations in curtain walls, such as shadow boxes or spandrel areas.

The use of glass in windows and curtain walls, in residential as well as in high-rise buildings, is something that requires great care in design and execution. Apart from complying with typical structural engineering practices and ensuring, for example, that the glass thickness is sufficient to withstand wind loads, impact loads etc. it is necessary always also to consider the thermal-stress resistance of the glass employed as well as the temperature distribution across glass and façade components. This topic is not new as it began to be analysed with the emergence of the first body tinted basic glass types. All the analysis done today is based on a linear approach and a more or less simplified algorithm. But modern constructions make it necessary to recognize special details and to acquire a more detailed view of the construction and use of such windows and curtain walls. Glass manufacturers can assist in this by helping to analyse the thermal stress characteristics but also...

The use of glass in windows and curtain walls, in residential as well as in high-rise buildings, is something that requires great care in design and execution. Apart from complying with typical structural engineering practices and ensuring, for example, that the glass thickness is sufficient...

In present-day practice, monitoring the installation process and the utilisation of glass and hybrid components, e.g. glass/steel or glass/plastic, has become increasingly important. To date, the quality control options for built-in glass is limited. It is not yet possible to provide a clear short-term statement regarding a potential irregular stress; this may arise due to the incorrect assembly of a glass fitting, for example. There are no accepted standard procedures to evaluate the in-situ stress condition of a built-in glass. The intention of this paper is to address this gap with the aid of photoelasticity as an indirect measuring method in a coordinated way with numerical simulation based on finite element analysis. To measure the two-dimensional qualitative stresses in glass and plastic components, a concept and a functional model for a mobile device, including user software, will be developed. By recording photoelastic measurements with this proposed mobile measuring unit, a qualitative statement about the glass stress behaviour for bonded and mechanical connections can be defined and converted into a quantitative statement via a correlation of experimental and numerical results. This article describes the associated framework for experimental investigations and numerical simulations for bonded and mechanical joints in glass constructions.

In present-day practice, monitoring the installation process and the utilisation of glass and hybrid components, e.g. glass/steel or glass/plastic, has become increasingly important. To date, the quality control options for built-in glass is limited. It is not yet possible to provide a clear short-term statement regarding a potential irregular stress; this may arise due to the incorrect assembly of a glass fitting, for example. There are no accepted standard procedures to evaluate the in-situ stress condition of a built-in glass. The intention of this paper is to address this gap with the aid of photoelasticity as an indirect measuring method in a coordinated way with numerical simulation based on finite element analysis. To measure the two-dimensional qualitative stresses in glass and plastic components, a concept and a functional model for a mobile device, including user software, will be developed. By recording photoelastic measurements with this proposed mobile measuring...

In present-day practice, monitoring the installation process and the utilisation of glass and hybrid components, e.g. glass/steel or glass/plastic, has become increasingly important. To date, the quality control options for built-in glass is limited. It is not yet possible to provide a clear...

An analytical approach based on the on the sequential partitioning of the data and Weibull Statistical Distribution for inhomogeneous - defective materials is proposed. It allows assessing the guaranteed strength of glass structures for the low probability of fracture with a higher degree of reliability. Parameters of equations for the piecewise linear approximation for Weibull statistical distribution have been defined on the example of processing of bending tests results for float glass. The advisability of using this approach to structural elements of different size is proved. It was shown that excluding the minimum values from the sample does not lead to the uni-modal distribution. A group of values, forming the lower branch of the distribution, appears again. Statistical analysis of the distribution curves made it possible to identify groups of defects, the technological removal of which would ensure an increase in the guaranteed level of strength. The results are the basis for solving optimization problems when you need to get a guaranteed level of strength for a given probability of fracture with minimal costs for glass element manufacture and treatment.

An analytical approach based on the on the sequential partitioning of the data and Weibull Statistical Distribution for inhomogeneous - defective materials is proposed. It allows assessing the guaranteed strength of glass structures for the low probability of fracture with a higher degree of reliability. Parameters of equations for the piecewise linear approximation for Weibull statistical distribution have been defined on the example of processing of bending tests results for float glass. The advisability of using this approach to structural elements of different size is proved. It was shown that excluding the minimum values from the sample does not lead to the uni-modal distribution. A group of values, forming the lower branch of the distribution, appears again. Statistical analysis of the distribution curves made it possible to identify groups of defects, the technological removal of which would ensure an increase in the guaranteed level of strength. The results are the basis...

An analytical approach based on the on the sequential partitioning of the data and Weibull Statistical Distribution for inhomogeneous - defective materials is proposed. It allows assessing the guaranteed strength of glass structures for the low probability of fracture with a higher degree of...

The classical image of glass is that of a rigid, transparent brittle material characterized by a non-crystalline microstructure. This 19th and 20th century image however is mostly based on the contrast between soda lime glass and metals. It does not really make sense in the 21th century where more modern testing methods have increased our understanding of the physiochemistry of glass. Based on recent results and the development of computational molecular dynamic software modelling a new approach to the physiochemistry of glass is outlined. The consequences this view has on glass properties and processing are explained.

The classical image of glass is that of a rigid, transparent brittle material characterized by a non-crystalline microstructure. This 19th and 20th century image however is mostly based on the contrast between soda lime glass and metals. It does not really make sense in the 21th century where more modern testing methods have increased our understanding of the physiochemistry of glass. Based on recent results and the development of computational molecular dynamic software modelling a new approach to the physiochemistry of glass is outlined. The consequences this view has on glass properties and processing are explained.

The classical image of glass is that of a rigid, transparent brittle material characterized by a non-crystalline microstructure. This 19th and 20th century image however is mostly based on the contrast between soda lime glass and metals. It does not really make sense in...

In structural design the bending strength of heat-treated glass is in general calculated as the simple sum of the characteristic values of the strength of annealed glass and of the thermally-induced prestress, considered as the 5% quantiles of the corresponding statistical distributions. However, the probability that two stochastic variables attain small values simultaneously is quite low; therefore, it is expected that the 5% quantile of the heat-treated glass strength is higher than the simple sum of the 5% quantiles of the two constituent distributions. Here, we theoretically confirm this result by assuming a two-parameter Weibull distribution for the population of annealed glass strengths and a Gaussian distribution for the thermal stresses. Although recent studies have confirmed that the two-parameter Weibull distribution cannot properly interpret the left-hand-side-tail of the annealed-glass strength population, it is here shown that the statistical competition with the surface prestress lowers the importance of a very precise interpretation of the left-handside tail. Remarkably, since glass strength is governed by the opening of surface cracks in mode I, the expected statistical interference is strongly affected by the type of stress state. If the stress state induced by external actions is equibiaxial, all cracks have the same opening stress, but if it is uniaxial, many cracks will remain closed under the sole effect of the prestress, which is in general uniform and equibiaxial. The higher the surface compression is and the closer to the uniaxiality the stress state is, the higher the number of “not-active” cracks will be. We believe that this study will promote and guide the design of ad hoc experimental campaigns for experimental validation.

In structural design the bending strength of heat-treated glass is in general calculated as the simple sum of the characteristic values of the strength of annealed glass and of the thermally-induced prestress, considered as the 5% quantiles of the corresponding statistical distributions. However, the probability that two stochastic variables attain small values simultaneously is quite low; therefore, it is expected that the 5% quantile of the heat-treated glass strength is higher than the simple sum of the 5% quantiles of the two constituent distributions. Here, we theoretically confirm this result by assuming a two-parameter Weibull distribution for the population of annealed glass strengths and a Gaussian distribution for the thermal stresses. Although recent studies have confirmed that the two-parameter Weibull distribution cannot properly interpret the left-hand-side-tail of the annealed-glass strength population, it is here shown that the statistical competition with the...

In structural design the bending strength of heat-treated glass is in general calculated as the simple sum of the characteristic values of the strength of annealed glass and of the thermally-induced prestress, considered as the 5% quantiles of the corresponding statistical distributions....

Glass strength is very sensitive to damage accumulation during its service life. Repair methods for glass have been proposed over the last decades to volumetrically fill or remove existing flaws from the surface of glass. However, the lack of information on the strength recovery attributable to glass repair methods restrict their use to low consequence class applications in buildings thereby making replacement of damaged installed glass the only safe and practical solution when dealing with damaged glass. Repair methods involving volumetric filling of visible flaws with resins, removal of visible flaws with polishing and chemical repair with acid treatment of visible flaws are undertaken in this study to investigate the strength recovery in 60 artificially aged annealed glass specimens. It is found that the polishing provides the most promising strength recovery results showing a 132 and a 40% increase in design and mean strength whilst the acid treatment provides the worst performance. Polishing repairs are further investigated in this study to determine their efficacy in strength recovery after environmental ageing (exposure to UV, humidity and freeze-thaw cycles).

Glass strength is very sensitive to damage accumulation during its service life. Repair methods for glass have been proposed over the last decades to volumetrically fill or remove existing flaws from the surface of glass. However, the lack of information on the strength recovery attributable to glass repair methods restrict their use to low consequence class applications in buildings thereby making replacement of damaged installed glass the only safe and practical solution when dealing with damaged glass. Repair methods involving volumetric filling of visible flaws with resins, removal of visible flaws with polishing and chemical repair with acid treatment of visible flaws are undertaken in this study to investigate the strength recovery in 60 artificially aged annealed glass specimens. It is found that the polishing provides the most promising strength recovery results showing a 132 and a 40% increase in design and mean strength whilst the acid treatment provides the worst...

Glass strength is very sensitive to damage accumulation during its service life. Repair methods for glass have been proposed over the last decades to volumetrically fill or remove existing flaws from the surface of glass. However, the lack of information on the strength recovery attributable...

The results from a new numerical method for simulating the strength and fracture locations of small glass specimens subjected to double ring bending are compared with experimental data. The method implements the weakest-linkprinciple while assuming the existence of Griffith flaws. A Weibull distribution for the strength is simulated based on a single population of Pareto distributed crack sizes. The effect of using different fracture criteria is investigated. An alternative distribution is simulated based on two populations of flaws. This distribution models the apparent bimodality in the empirical data set. The numerical method is dependent on a representation of the surface flaws condition in glass. As new techniques become available for examining the surface characteristics, this numerical method is promising as a Glass Strengthmeans for modelling the strength better than current methods do.

The results from a new numerical method for simulating the strength and fracture locations of small glass specimens subjected to double ring bending are compared with experimental data. The method implements the weakest-linkprinciple while assuming the existence of Griffith flaws. A Weibull distribution for the strength is simulated based on a single population of Pareto distributed crack sizes. The effect of using different fracture criteria is investigated. An alternative distribution is simulated based on two populations of flaws. This distribution models the apparent bimodality in the empirical data set. The numerical method is dependent on a representation of the surface flaws condition in glass. As new techniques become available for examining the surface characteristics, this numerical method is promising as a Glass Strengthmeans for modelling the strength better than current methods do.

The results from a new numerical method for simulating the strength and fracture locations of small glass specimens subjected to double ring bending are compared with experimental data. The method implements the weakest-linkprinciple while assuming the existence of Griffith flaws. A...

Many glass applications require laminated glass to achieve a safe load-bearing behaviour. Beside the structural aspect, glass elements have to meet high aesthetic demands. Laminated glasses often feature an offset between the individual glass panes resulting from the lamination process. With regards to visible or exposed edges, this displacement reduces the aesthetic quality of the glass component. The regrinding of the edge after lamination equalises the offset and thus creates a smooth surface. However, regrinding tempered glass leads to a reduction of the surface compression zone at the edge and may decrease the load-bearing capacity. A research project focuses on the detailed evaluation of the effect of regrinding tempered glass. To attain a precise understanding, three different aspects have to be examined: first the maximum required grinding depth resulting from the edge offset, second the defects on the surface of the edge and third the residual stress distribution. The third part was examined by means of stress measurements at the edge and the surface of different specimens. Glass beams made of fully tempered glass and heat strengthened glass with three different thicknesses (6, 8 and 10 mm) were ground after the tempering process. The regrinding depth was 1, 2 and 3 mm. One group of specimens remain untreated as a reference. The depth of the compression zone and the magnitude of the surface stress at the edge were measured with the help of photoelastic measurements. The experimental approach and the results are the content of this paper. It enables a statement about transformations of the residual stress state at the edge owing to regrinding tempered glass.

Many glass applications require laminated glass to achieve a safe load-bearing behaviour. Beside the structural aspect, glass elements have to meet high aesthetic demands. Laminated glasses often feature an offset between the individual glass panes resulting from the lamination process. With regards to visible or exposed edges, this displacement reduces the aesthetic quality of the glass component. The regrinding of the edge after lamination equalises the offset and thus creates a smooth surface. However, regrinding tempered glass leads to a reduction of the surface compression zone at the edge and may decrease the load-bearing capacity. A research project focuses on the detailed evaluation of the effect of regrinding tempered glass. To attain a precise understanding, three different aspects have to be examined: first the maximum required grinding depth resulting from the edge offset, second the defects on the surface of the edge and third the residual stress distribution. The...

Many glass applications require laminated glass to achieve a safe load-bearing behaviour. Beside the structural aspect, glass elements have to meet high aesthetic demands. Laminated glasses often feature an offset between the individual glass panes resulting from the lamination process. With...

This work presents the relation between the fragment density and the permanent residual stress in fragmented tempered glasses of various thicknesses. Therefore, fracture tests were carried out on tempered glass plates and the fragments in observation fields of 50 mm × 50 mm were counted. The average fragment density in the observation fields was set in correlation with the average measured residual stress of each specimen. Furthermore, the average particle weight of 130 particles per specimen chosen by random was determined. The relation between the average particle weight and the measured residual stress is given. The volume and the base surface as well as the radius of the particles are calculated assuming cylindrical fragments with approximately unchanged thicknesses. The relation between the residual stress and the particle base surface of regular polygonal shapes n=3–8 edges in addition to the cylindrical fragment (n→∞) is also determined. The glass used for the fracture tests was commercial soda-lime-silica glass with three different thicknesses 4, 8 and 12 mm. The results in this work are a basis for the establishment of a theoretical model to predict macro-scale fracture patterns from elastic strain energy in tempered glass.

This work presents the relation between the fragment density and the permanent residual stress in fragmented tempered glasses of various thicknesses. Therefore, fracture tests were carried out on tempered glass plates and the fragments in observation fields of 50 mm × 50 mm were counted. The average fragment density in the observation fields was set in correlation with the average measured residual stress of each specimen. Furthermore, the average particle weight of 130 particles per specimen chosen by random was determined. The relation between the average particle weight and the measured residual stress is given. The volume and the base surface as well as the radius of the particles are calculated assuming cylindrical fragments with approximately unchanged thicknesses. The relation between the residual stress and the particle base surface of regular polygonal shapes n=3–8 edges in addition to the cylindrical fragment (n→∞) is also determined. The glass used for the...

This work presents the relation between the fragment density and the permanent residual stress in fragmented tempered glasses of various thicknesses. Therefore, fracture tests were carried out on tempered glass plates and the fragments in observation fields of 50 mm × 50 mm were counted. The...

Structural Glass Design Philosophy & Structural Safety

Due to the recent terrorist attacks, the market demand for security glazing has rapidly grown and turned from a “bank counters” market to a facade market. In this context, it appears to be legitimate to ask the question of the applicability of current standards to this changing environment: Are they still adapted to fulfil the security requirements of the market ? If not, which adaptations could be performed ? In the present talk, the current European standards dedicated to the security glazing resistance against explosion pressure - EN 13541 - is reviewed and compared to its ISO standard pendant - ISO 16934 - and alternative - ISO 16933 -. Moreover, based on numerical simulations, the current extension rules applicable to the specific case of the explosion resistance of insulating glazing units - EN 1279-5 - are discussed as well.

Due to the recent terrorist attacks, the market demand for security glazing has rapidly grown and turned from a “bank counters” market to a facade market. In this context, it appears to be legitimate to ask the question of the applicability of current standards to this changing environment: Are they still adapted to fulfil the security requirements of the market ? If not, which adaptations could be performed ? In the present talk, the current European standards dedicated to the security glazing resistance against explosion pressure - EN 13541 - is reviewed and compared to its ISO standard pendant - ISO 16934 - and alternative - ISO 16933 -. Moreover, based on numerical simulations, the current extension rules applicable to the specific case of the explosion resistance of insulating glazing units - EN 1279-5 - are discussed as well.

Due to the recent terrorist attacks, the market demand for security glazing has rapidly grown and turned from a “bank counters” market to a facade market. In this context, it appears to be legitimate to ask the question of the applicability of current...

In this paper authors will summarise current design approaches for hybrid glass structures. Our past and present projects will be used to demonstrate how such structures can be justified using finite element analysis, analytical solutions in context of prescriptive national and international regulations, industry guidance’s developed and accumulated over past decades. General methods will be distilled, relevant for future hybrid glass structures.

In this paper authors will summarise current design approaches for hybrid glass structures. Our past and present projects will be used to demonstrate how such structures can be justified using finite element analysis, analytical solutions in context of prescriptive national and international regulations, industry guidance’s developed and accumulated over past decades. General methods will be distilled, relevant for future hybrid glass structures.

In this paper authors will summarise current design approaches for hybrid glass structures. Our past and present projects will be used to demonstrate how such structures can be justified using finite element analysis, analytical solutions in context of prescriptive national and international...

Current design codes and standards provide limited indications for advanced analysis and earthquake engineering of structural glass applications in seismic regions. This work provides an energy-based approach for efficient design and structural performance evaluation of structural glass systems in seismic regions. The analytical formulation of the energy-based approach for dissipative non-linear structural glass systems is firstly presented. A practical application is then described by means of analytical and numerical studies. The results show that the combination of appropriate structural design with advanced non-linear analysis allows the achievement of highly efficient design and satisfactory performances comparable to the ones of other common structural systems.

Current design codes and standards provide limited indications for advanced analysis and earthquake engineering of structural glass applications in seismic regions. This work provides an energy-based approach for efficient design and structural performance evaluation of structural glass systems in seismic regions. The analytical formulation of the energy-based approach for dissipative non-linear structural glass systems is firstly presented. A practical application is then described by means of analytical and numerical studies. The results show that the combination of appropriate structural design with advanced non-linear analysis allows the achievement of highly efficient design and satisfactory performances comparable to the ones of other common structural systems.

Current design codes and standards provide limited indications for advanced analysis and earthquake engineering of structural glass applications in seismic regions. This work provides an energy-based approach for efficient design and structural...

Challenging Glass Conference Proceedings collects the conference articles presented at the international bi-annual Challenging Glass Conference and focuses on the Architectural and Structural Application of Glass.